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Board
/sci/ - Science & Math

>what is /sqt/ for?
Questions regarding maths and science. Also homework.
>where do I go for advice?
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (lAtEx)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
>where can I look up if the question has already been asked here?
warosu.org/sci
eientei.xyz/sci
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com

>where can I get:
>books?
libgen.rs
z-lib.org
stitz-zeager.com
openstax.org
activecalculus.org
>articles?
sci-hub.st
>book recs?
4chan-science.fandom.com/wiki//sci/_Wiki
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com

>attach an image (animal images are ideal. Grab them from >>>/an/)
>recheck the lAtEx before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not flipping that sideways picture
>don't ask for a hint if you want a solution
>xyproblem.info
>>
>>14843727
Does the well-ordering principle still work if I added zero to my set?
>>

Physics questions:
>>14824871

Maths questions:
>>14824164
>>14826921
>>14831178
>>14832279
>>14837829
>>14839525
>>14840314

Biology questions:
>>14829665

Engineering questions:
>>14837229

Stupid questions:
>>14823535
>>14823573
>>14824370
>>14825444
>>14826328
>>14827601
>>14829146
>>14829232
>>14829447
>>14829950
>>14831220
>>14831223 [inb4 "shouldn't this be in maths"]
>>14832250
>>14832272
>>14835676
>>14839260
>>14839912
>>14841661
>>14841724
>>14841776
>>
Why is it called Paleontology if the Paleozoic was up to 250 mya
>>
What's the motivation for matrix matrix multiplication exactly? Like I understand how to do it, I just don't get what the significance of the result is when the RHS matrix has more than one column
>>
>>14843789
If you have matrices $A$ and $B$ and a vector $v$, we have $A(Bv) = (AB)v$. That's the motivation.
>>
>>14843789
For finite dimensional vector spaces, every linear map (a function with certain desirable properties) can be represented by a matrix. Composing these functions is precisely what matrix multiplication is, even though admittedly the formula looks random at first
>>
How the fuck does one find the last 2?
>>
>>14843765
Yes, the principle is for all sets. For this particular case you can construct it easily enough, take the well-ordering from your original set, then append the new element to the top, and it’s again a well-ordering. (Actually you could place it at the bottom or in the middle and it would still be a well-ordering. But on top is better practice because it keeps working if you add infinitely many elements.)
>>
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>>14843727

Stupid question: Why did they put a HERV trigger in a mandated injection?

>Sars-CoV-2 Spike Protein Activates Human Endogenous Retroviruses ( HERV-W )

>https://www.medrxiv.org/content/10.1101/2022.01.18.21266111v2

>https://pubmed.ncbi.nlm.nih.gov/?term=HERV-W

>>
>>14843823
>literal, blatant: do my homework post
>>
It took me 3 weeks just to understand and solve most of the problems in the first chapter of Lang's algebra book.
Am I doomed to never be able to self learn math?
>>
>>14843870
no. learning process is not linear. You go slow at first, then as you learn and gain more experience, new problems are more 'atack-able' (?), I mean, you will face them with more vision and skill that you've earn in the past.

Once it took me 3 weeks to solve a single problem. Nothing made sense. I tried over and over, changing approaches and shit. one day I woke up and gave it another good try. And the motherfucker was over. I have experienced this a good few times, and each is like facing a new boss battle with not knowing shit about what t do.
Another time I saw a problem in a book and I was like 'nah man, I'll never figure this shit out on my own', but asking for help someone gave me the right suggestion I needed, and again, done. After months of looking at that particular problem feeling it was utterly impossible I made it mine.

Keep it going anon. This is a game of patience and effort. And try to work smartly. But only experience will give you this.
>>
>>14843882
Thanks a lot anon. I really appreciate it.
>>
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>>14843887
np anon. Btw, sometimes is good to let problems sink in your mind before giving them another try.
>>
>>14843856
I don't give a fuck if I answer 2 more questions correctly on a 40 problem assigned, which makes up 2% of my final grade. I asked "how do you slove these" not "give me the answers". I need to understand the approach to solving these so I'll have a better understanding of the chapter material as a whole.
>>
>>14843901
magnitude of velocity is $\sqrt{h^2+v^2}$ where $h$ is horizontal component and $v$ its vertical component.
For the angle, I guess if we are dealing with parabolic shot, it should be the same as the starting angle if it was thrown at the same height as it hit the ground.
>>
>>14843823

8.5 i is constant
j as a function of time is 3.5-9.81*t
turn i and j into a triangle
use trigonometry to find the hypotenuse length (magnitude) and angle
>>
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>>14843727
Does anybody know what is this molecule? I'm too retarded to read it
>>
>>14843924
3,4,5-trimethoxyphenylethanamine
also known as mescaline you degenerate junkie
>>
why is air a good insulator?
>>
>>14843727
What does childbirth feel like? How can I simulate it as a biological male?
>>
>>14843937
(assuming you mean thermal insulator)
on a molecular scale, heat is transferred through collisions of particles
in a gas, there are much fewer particles and much fewer collisions to transfer the heat than there are in solids
>>
hey guys im sure this place will prove more useful than the physics general where nobody posts.

i need good book recommendations on the following 4 courses i have in the upcoming semester (physics undergrad 2nd year):

analytical mechanics
numerical methods for physics
methods in theoretical physics 1 (literal translation of the course name, complex functions fourier transform etc)
waves, light and optics (1d wave equation, what are waves etc)

>>
>>14843765
It works for any set of integers which is bounded from at least one direction.
>>
>>14844133
I think you can't go wrong with numerical analysis books for numerical physics, you might get Monte Carlo algorithms for things like ISing models etc, in that case you might find comprehensive information on that in a good book for markov chains. In my case I used
>An introduction to Numerical Analysis By Suli and Mayer, very good but check the errata
>Markov Chains by J.R Norris Chapter 5 (monte carlo application, also covers Ising model)
Both are Cambridge University press. Markov chains have wide application anywayso you might like it.
For analyticsl mechanics, unless you are introduced to noetherian stuff, the book classical mechanics by taylor covers the Lagrangian and Hamiltonian formulation quite clearly, I haven't finished it beyond that so it might be more extensive than that.
>>
>>14843789
https://youtu.be/fNk_zzaMoSs
>>
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How is this function a homeomorphism for s<1, it isn't even well defined for the 0 vector then.
>>
>>14844385
Don't be silly, you know damn well that you can extend it to zero by continuity because $\| F_s (x) \| = \| x \|^s$
>>
>>14844402
Well if they extend it to zero why didn't they say so?
>>
>>14844411
Because it's obvious unless you're being intentionally obtuse.
>>
>>14843727
Is there a name for when you have two finite topological spaces defined for the same set?
>>
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I'm confused. I know how do nodal analysis roughly but I kept getting the answer wrong because I set up my KCL equation as
-2.3 + (x - 60)/(1) + x/50 = 0

whereas I was supposed to do this:
-2.3 + ((x - 60)/ (1 + 4)) + x/50 = 0

Treating the 1 and 4 ohm resistors as a series but why would I do that when there's a voltage source between them? Someone on stackexchange(https://electronics.stackexchange.com/questions/188051/combining-resistors-in-series-with-a-voltage-source-in-between) asked a seemingly similar question and got a definite no on treating the two elements as a series. I'm confused.
>>
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can someone explain this to me
I get that the factoring and after he creates the piecewise function I understand how he got the limits but I don't understand how he goes from the factored function to the piecewise function. I'm guessing it has to do with the absolute value?
>>
>>14844725
> I'm guessing it has to do with the absolute value?
Correct.

|x - 2| = x - 2 if x>2, and |x - 2| = - (x - 2), if x < 2

just plug in some values to see it for yourself.
>>
Anyone in the medical field know what the future implications of vaping are? The main issue with smoking is its long term effects. Have we found any known carcinogens/toxic substances in disposable vapes that are currently flying under the radar?
Do you hypothesize that they'll be worse or better than cigarettes?

Diacetyl is already known, but that's generally not used unless you want to flavour something as butter.
>>
>>14844922
okay so basicaly (x+3) is always 5 but (x-2) is either times a trivial negative or times a trivial positive. and that cancels out with whatever the absolute value is leaving only the sign which is why 5 is not reduced to 0.5

So if the absolute value was not there then it would be -0.5 or 0.5?
>>
>>14844990
If there was no absolute value g(x) would always just be x+3 for all x. It would not be piecewise.
>>
>>14845006
sry I meant if the |x-2| was entirely removed not just the absolute value signs
>>
>>
>>14845721
All the kids who used to come here are done with school.
>>
>>14845721
It's not like it's a fast thread to begin with.
>>
>>14845735
>>14845768
>>
>>14845775
First guy, I am here to see if I can answer any questions.
>>
>>14845781
how often you refresh the page
>>
>>14845803
I track it. So I just visit when I come back and see there is a reply. I don't autistically keep it open and refresh it if that's what you are asking.
>>
>>14845721
It's not, this is normal. One thread a week.
>>
How can I buy chemicals in the UK as an individual? Our laws tightened after the bus terrorist attack. Buying sulphuric acid is also really difficult due to certain faggots.

Could I start a chemical importing business? I think this is naive because I would have to account for everything bought and sold.

I want to do some independent research in the area of cosmetics, but it seems that this is now illegal in the UK. What has this country come to?
>>
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reposting, need help with the indicator function part
>>
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Can someone explain to me whats going on
As far as I can tell I use 4 in place of x becasue thats where x is either less than or greater than??

Does that mean I won't get any like x<5, x>3

Than he sets both equations equal to each other and then gets all terms on one side and then you treat it like a vertical asymptote and set it equal to 0?

I don't really understand what happening but are those the correct steps.
>>
>>14846353
> Can someone explain to me whats going on
The magic word is continuous. This means that at the point $f(4)$ both of parts of the piecewise functions must be equivalent since there can't be a discontinuity between $f_-(4)$ and $f_+(4)$. After that it's simply a case of solving for c.
>>
If life is just a simulation and all, what is the best way to figure out how the fuck to shut it down?
>>
>>14846353
You're the same retard who was asking how did a piecewise function came into the limit?
Read the theory before attempting problems fag.
>>
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>>14846353
>>
>relativity say space and time are unbounded but probably not infinite
huh? How? And how is 'unbounded' different from 'infinite'?
>>
>>14846788
https://physics.stackexchange.com/questions/247864/what-does-finite-but-unbounded-universe-mean
>tl;dr it's geometry
>>
>>14846788
Is the surface of the earth infinite? It has no boundary.
>>
>>14846577
Try every switch you see until it shuts off. It is now your life's purpose.
>>
>>14844415
So i just need to assume functions are equal to their continuous extension?
>>
I’m a college dropout (financial reasons) saving up for an EE degree, I expect to be able to afford it in 3-5 years or so AT MOST
What are some essential topics and books I should proactively go through? I’m 20 with some pre-existing background with Integrals and Riemann stuff but that was a year ago
>>
>>14847468
Just look at the syllabus of the college you want to apply and study accordingly.
>>
>>
>>14847519
Damn, that was a stupid question yeah
Thanks anon, I'll need to decide on a uni then
>>
>>14847545
>Damn, that was a stupid question
Look at the name of the thread.
>>
How many mg of aspirin for covid?
>>
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When I cook homemade wonton dumplings made with ground beef, why does the meat turn into a single piece?
>>
>>14846702
>>14846751
Is it really that obvious, I;ve never really gotten why certain steps are taken in math. I've always just tried to replicate the steps taken on youtube help videos.
>>
>>14847649
Dude read a book. Is this Analysis or Calculus?
>>
>>14847538
yep, this is a groomer thread for sure
>>
>>14847661
Calculus
Which book do you recommend, I don't know any latin or greek
>>
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I would like to approach a team of scientists from Israel some time within the next couple years about the possibility of volunteering for a Autologous Pancreatic islet transplant into my spinal cord or in the subarachinoid space in my brain to promote my cognition.
The procedure has been done in mice with a consistent record of success.
> Intracranial Transplantation of Pancreatic Islets Attenuates Cognitive and Peripheral Metabolic Dysfunctions in a Rat Model of Sporadic Alzheimer's Disease
https://pubmed.ncbi.nlm.nih.gov/30175977/

I would also like to approach a team of doctors in Columbia which would be able to transplant fetal/ umbilical cord stem cells into the subarachinoid space in my brain and ask them to inject the stem cells alongside a hydrogel modified YIGSR/IKVAV peptide to support ~30 fold increased survival of the transplanted stem cells. I would be supplying the peptides myself.

How would I ask for this without sounding insane or without any ethics board scrutinizing the ideas.
>>
>>14847669
If you just wanna survive through school, I guess that Stewart book is fine. I haven't read it but from what I know, it's written for retards.
>>
>>14847723
what are the books for non-retards
>>
>>14846523
That seems too simple I really just substitute 4 and treat it like an aglebra problem
>>
is there a way to make my penis smaller? it's genuinely uncomfortably large and I'm getting sick of it
>>
I'm reading an aerospace engineering drawing from the 50s and translating to modern times.

What the hell is this notation? How do I read it?

The variable is equal to: 20689655 48-, or 11093306 51

Where the hell do I put the decimal? I think the first one is a negative number because of the dash after 48.
>>
>>14847743
Pick up a book on proofs. Read Cauchy Schwarz Master class. Then read Stephen Abbot: Understanding Analysis. But I think you might be too retarded for this route. Unretarding yourself would require reading many more proof based books on unrelated topics. Not recommended unless you intend to pursue mathematics.
>>
>>14847845
post a photo
>>
>>14847845
I cant right now. But what I posted is literally all it says. I have a hundred tables of Xf, Yf, Zf values.
I found a couple definitions.

Yf = 20 ------> 20000000 52
Yf = -4.278 -------> 42780000 51-

But got a lot with 48, -46 tagged on the end with no definitions
>>
Why does sauerkraut smell worse during the first few days of fermentation than it does afterward?
>>
>>14847862
>>14847871
>>
>>14847846
How did I end up so retarded
>>
>>14847872
them bacteria niggas be vibing hardcore but then they get tired and chill out
>>
>>14847882
By looking at YouTube videos. But don't worry, I am assuming you are in school so you are probably underaged. I didn't unretard myself until near my graduation.

Here is the full list if you are interested.
>$\text{Velleman, D.J. } ( \oldstyle{1994}). \textit{ How to prove it.}$
Do everything.
>$\text{Montgomery, H.L., Niven, I., & Zuckerman, H.S.} ( \oldstyle{1957}). \textit{ An introduction to the theory of numbers.}$ AND $\text{Long, T.C. } ( \oldstyle{1965}). \textit{ Elementary introduction to number theory.}$
Will help with writing proofs. Solve everything upto congruence. Then skip unless you find Number Theory interesting.
>$\text{Artin, M. } ( \oldstyle{1991}). \textit{ Algebra.}$
Will help getting used to abstraction. Do as much as you can.
>$\text{Friedberg, S.H., Insel, A. J., & Spence, L.E. } ( \oldstyle{1979}). \textit{ Linear algebra.}$
You should do the whole thing, will prepare you for multivariable analysis. Watch 3blue1brown's series on Linear Algebra first.
>$\text{Enderton, H.B. } ( \oldstyle{1977}). \textit{ Elements of set theory.}$
Gives context to Analysis and most of modern mathematics.
>$\text{Steele, J. M. } ( \oldstyle{2004}). \textit{ Cauchy-Schawrz master class.}$
Prerequisite for Calculus/Analysis.
>$\text{Amann, H., & Escher, J. } ( \oldstyle{2005}). \textit{ Analysis.}$
Very difficult but comprehensive book on Analysis. Watch 3blue1brown's series on Calculus first.
>$\text{Abbott, S. } ( \oldstyle{2000}). \textit{ Understanding analysis.}$
Do this if the former is too difficult, or if you want to get to the meat of Analysis faster.
>>
>>14847900
The yeast you mean
>>
>>14847747
Yes it really is that simple as long as you understand everything the question is telling you.
>>
>>14847871
damn, nobody?
>>
>>14847904
thx anon I'll look into it
>>14847988
eh kind of, but the test is tomorrow so I'll focus on memorizing how to solve the problems for now and get started on everything else after the test
>>
>>14848242
nobody wants you groomers here, thats why your thread is getting ignored
>>
>>14846351
https://towardsdatascience.com/why-sample-variance-is-divided-by-n-1-89821b83ef6d
>>
>>14846351
https://www.quora.com/What-is-the-relationship-between-sample-mean-variance-and-population-variance-Can-they-be-equal
>>
Why is voltage current times resistance and not just current minus resistance? Voltage also seems to be no different to current. I guess it factors resistance.. but then doesn't current if it's electrons/second? New to all this...
>>
>>14848913
Also how are watts different from power? It's both just energy/s isn't it? Or is one the output and one the ability to do work with it?
>>
>>14848917
watts are a unit of power, like how there are different units of length (mile, km, etc...).
>>14848913
current flows from high voltage potential to low voltage potential. think of it as a ball on the top of the hill. the ball has gravitational potential energy at the top and will roll down where it has lower gravitational potential. current works similarly. you can also think of temperatures/heat transfer as an example, heat will always move from a hotter object to a cooler object
>>
How do I prove that second lemma?
>>
>>14849065
You select a
0 < h < (a - y^2)/(2y + 1)
in the first part and you select a
0 < h < (a - y^2)/(2y)
in the second part.
>>
>>14847688
tell them you're a transintellectual
>>
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How do I integrate over a group?
This book doesn't want to explain it. Any book recommendations for it?
>>
What is the sequential definition of limits and continuity for a function with two variables?
>>
>>14849446
>>14849577
Like "$a_{i, j}$ is a sequence on two variables, what's $\lim_{i, j \to \infty} a_{i, j}$?" That's not really a thing.
>>
>>14849577
Same as for functions in one variable.

[eqn] \lim_{(x,y) \to p} f(x,y) = L [/eqn]
iff for every sequence with $\lim_{n \to \infty} (x_n, y_n) = p$ we have $\lim_{n \to \infty} f(x_n,y_n) = L$.
Let $U \subset \mathbb{R}^2$. A function with domain $U$ is continuous iff for every $p \in U$:
[eqn] \lim_{(x,y) \to p} f(x,y) = f(p) [/eqn].
>>
>>14849640
Yeah thanks, I just had a brainlet moment where I forgot I could apply Eucilidean norm to convergence of vector sequences.

>>14849637
That is a thing.
[eqn] \lim_{m,n} a_{mn} = a \iff \forall \epsilon > 0 \; \exists N \; \forall m,n \geq N \; \;|a_{mn} - a| < \epsilon [/eqn]
>>
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Can someone walk me through this, I need to use the difference quitient so

f(x+h)-f(x)
_________
h

that means wherever there is an h in 3h^2 + 5h
I change it to x + h right??

But that doesn't look like what my professor is doing
>>
>>14849741
> I change it to x + h right??
yes
> But that doesn't look like what my professor is doing
yes it is. the very first limit equation he writes is precisely that, just change x to 2
>>
[eqn]
\frac{dF}{dt}=f(F,G,H)\\
\frac{dG}{dt}=g(F,G,H)\\
\frac{dH}{dt}=h(F,G,H)
[/eqn]

I have this set of equations that I want to solve with the Runge-Kutta 4th order method. Are the intermediate steps shown bellow correct?

[eqn]
k1=f(F,G,H)\\
k2=f(F+k1*dt/2,G+k1*dt/2,H+k1*dt/2)\\
k3=f(F+k2*dt/2,G+k2*dt/2,H+k2*dt/2)\\
k4=f(F+k3*dt,G+k3*dt,H+k3*dt)
[/eqn]
>>
>>14849756
Oh right because x is already given, so I can subtract f(x+h) - f(x) because I already know what x is

What about the first part of the original equation
f(2+h)-f(2), what is that and what is it for
>>
>>14849761
> what is it for
it's not for anything, it's just a given. I get the feeling you really don't understand the question and just want to cut & paste an answer.
>>
>>14849721
That's $\lim_{min(m, n) \to \infty} a_{m, n}$ and it's not really compatible with i.e. limits at infinity for complex functions.
>>
>>14849778
>complex functions
>>
>>14849768
You're right I have a test today so I'm cramming, but next I promise I'll develop a deeper understanding of the material
>>
>>14849920
I think I bombed my test :(
>>
>>14850972
Given all your recent questions and clear lack of understanding that is not a surprise. It's hard to bluff a math test.
>>

We get a big empty sphere with a hole in the top and bottom, we then fill the sphere with some kind of denser-than-uranium liquid material that is designed to absorb neutrons, and then put liquid fissile uranium in there too. These are both designed to mix when at rest. Then you just spin the sphere until the denser control material pushes the fissile material into a ball in the center. The faster you spin, the more the fissile material gathers in the center, the slower you spin, the more they mix.

You use the absorptive material as the heat conductor away from the reactor. New liquid control rod is pumped into the ceiling of the sphere, it's spun around the outside of the thing, and then exits the bottom of the sphere, heated by the reaction.

In the case of power loss or shutdown, the sphere slows down, the liquid control rods and fissile uranium mix, and the reaction stops.

Bonus: I don't see why you couldn't let this get pretty hot in the center if you use a big enough envelope of liquid neutron absorption fluid. Like, hot enough for the uranium and a large chunk of the envelop to turn to plasma.
>>
>>14849741
You again? Fuck off retard get out this thread and read a book.
>>
>>14851417
the spinning would separate everything, leading to just a uranium stage which would be unmoderated and either meltdown or fucking explode
compressing a spherical sample of fissile material is how the plutonium bomb "fat man" operated

all of this is on top of the fact that your "liquid uranium" solution doesn't exist, and that the entire thing is impossible to build practically speaking without 10^10 potential single-point failure modes, which generally isn't how you want to design a nuclear reactor
>>
>>14851446

That's the point. The spinning turns up the reaction, and slowing down slows down the reaction. And it's supposed to be hot. That's how it's liquid. Instead of the uranium melting being the fail state, the uranium is supposed to be liquid in this system.
>>
>>14851461
If you are spinning to separate your phases, there would be no "liquid control rod" present in the uranium stage. You would just be making an unmoderated nuclear reaction, which is a bomb.
>>
>https://youtu.be/EI_A4bCtNiE
So i dont get why it feels wrong, other than wikipedia and the media would be really uppity about this long unsolved problem being solved/proven, but is it really just that the Collatz conjecture as a whole converges towards one (1) because math i already forgot about? Most of the video is filler fluff anyways about a subtracting machine (3x+1 is really just adding 2x+1 and then you have to divide by 2 anyways because any odd number
>x/2=/=I
becomes even when you do 3x+1)
I just didnt wanna push a better thread off the board with this stupid shit
>>
>>14851469

You spin the thing at the exact speed you need to cause the bead of fissile uranium of the exact size you need to create the exact amount of heat you need to form in the center of the mix. It is "liquid control rod" in that the mixed portion of the liquid doesn't chain, and you can control how much of the fissile uranium is in the center via the speed of the turning motion. Which gives extremely easy control of the reaction. But even better, still works when the fissile uranium in the center starts getting crazy hot and like.. stops being a liquid and starts being a gas or a plasma. As long as you've got a large enough envelope of slightly more dense material to use as the envelope... and some use for all that power... you could get the center of this thing pretty hot and it will still keep working because the colder material is inherently denser and will push the hotter reacting material closer into the center of the reactor, even if a large chunk of the envelope is itself a plasma or a gas.
>>
What is the reflection of $(a,0)$ across $x=c$?
>>
It's not even that hard to build this thing or run it. It's just uses scary materials. Because it uses materials that are molten by default. You just fill the sphere with this molten uranium - absorption fluid mix, and run the fluid into the sphere, then back out of the sphere, into some heat exchanger, and then back again.

Then you spin the sphere some amount of speed, it will cause the fissile uranium to dissolve out of the mix in the center of the sphere, causing it to chain and power the reaction, which will heat the rest of the mix, to be used to power the heat exchanger.

You could even change how much uranium can dissolve out of the fluid by letting it cool down, slowing the spin, letting it mix more, then you filter the uranium out of the fluid outside of the reactor, or you can add more fissile uranium into the mix, where it will boil up into the center of the reactor when it gets there.
>>
The coolest thing about this is that i think you could build it so that it would get so crazy hot in the center, i think you could fuse stuff. And since the stuff we typically wanna fuse is much lighter than uranium, it would inherently bubble up into the center of the reactor if the molten mix fluid was impregnated with it.
>>
If -1<x<1 and -1<y<1
show that -1<xy<1?
>>
>>14843727
is there any hope for me if i did poorly in high school? graduated with a B+ last year and about to start engineering school this year.
>>
>>14851556
Assume $0 \leq y < 1$. Now, multiply $-1 < x < 1$ by $y$:
[eqn] -1 < -y \leq xy \leq y < 1 \[eqn]
Now assume the negation, and derive the same inequality.
>>
>>14851568
[eqn] -1 < -y \leq xy \leq y < 1 [/eqn]
>>
I looked through the common data set for the colleges I want to apply to, and based on the data being a woman roughly doubles your chances of getting in. Would there be any consequences for lying about being a woman? If anybody asks, I can just say that I'm still on a journey of exploring my gender and I ended up feeling like a man after all.
>>
>>14851556
Another proof using absolute value:
[eqn] 0 \leq |xy| = |x| |y| < 1 \ iff -1 < xy < 1 [/eqn]
>>
What is the highest vertebra a person can break and still
>a. get pregnant
>b. carry a child to term
>c. produce viable sperm
>d. get erection and ejaculate
I am trying to breed a quadrupletic master race
>>
>>14851130
Well he ended up asking questions that weren’t on the practice or were slightly different
Like
Sqrt(x^2+ax)-sqrt(x^2+bx) as x goes to infinite

I put something like 0 since I figured it would be infinite - infinite

I understand what I’m supposed to to I just didn’t get how to cancel terms and factor everything.

In general I think it was a lot harder than the practice.
>>
>>14851519
(a,2c)?
>>
>>14851717
>Sqrt(x^2+ax)-sqrt(x^2+bx) as x goes to infinite
Do you know how to apply conjugation and multiplying and dividing an equation on both sides?
>>
>>14851717
> since I figured
So you guessed because you have no idea what you're doing. I even remember you asked an almost identical question in an earlier thread.

$\lim_{x \to \infty}\ \sqrt{x^2 + ax} - \sqrt{x^2 + bx} \\ = \lim_{x \to \infty}\ (\sqrt{x^2 + ax} - \sqrt{x^2 + bx}) (\sqrt{x^2 + ax} + \sqrt{x^2 + bx}) / (\sqrt{x^2 + ax} + \sqrt{x^2 + bx}) \\ = \lim_{x \to \infty}\ ((x^2 + ax) - (x^2 + bx)) / (\sqrt{x^2 + ax} + \sqrt{x^2 + bx}) \\ = \lim_{x \to \infty}\ (ax - bx) / (\sqrt{x^2 + ax} + \sqrt{x^2 + bx}) \\ = \lim_{x \to \infty}\ (a - b) / (\sqrt{1 + a/x} + \sqrt{1 + b/x}) \\ = (a - b) / 2$
>>
>>14851519
>>14851725
It's $(2c-a,0)$
>>
What is your personal experience with or scientific opinion on things like Hemi-Sync and the gateway tapes?
What about guided meditation in general?
If you’re of the opinion that they actually work, do you think they’re useful for anything other than relaxation in day to day life? I’ve never come across any legitimate scientific support on any of the aforementioned things except for some very specific situations such as the effects of Hemi-Sync on people under general anesthesia.
>>
>>14851717
You must be 18 to post here.
>>
>>14851743
Oh right, I'm an idiot. I read it as y=c
>>
>>14841661
Anyone?
>>
>>14851727
I remember now but for some reason it didn't jump out for me as a possible solution
>>14851737
I get most of that but when you're dividing out the x from the terms you're using /x^2 right?
if so why does ax and bx reduce to a and b
wouldn't it be a/x and b/x
>>
>>14851873
how the fuck as you doing a course on limits if you don't even understand basic algebra??
>>
>>14851873
Its been years since I took algebra
>>
>>14851880
>>14851878
sry that post was for you
>>
>>14851880
>>14851881
still doesn't answer the question, in fact it makes it worse
>>
>>14851885
Why I am I taking a course on limits?
Its the next math course I need to take for comp sci degree
>>
>>14851887
And I was thinking this guy is still in school. They literally allow anyone in western universities don't they?
>>
>>14851892
I'm from a very a state with very poor education ranking, one of the worst in the country. My SAT were slightly higher than the national average but in the top 20% of state average. I never even went to highschool
>>
>>14851896
Yeah? and I am from a third world country where people can barely afford food, fuck off. Being retarded is one thing, but having zero drive to learn is inexcusable.
>>
>>14851910
But I'm going to college? why do you say I have zero drive to learn
>>
>>14851921
You're going to college because you want a job. The way you are asking questions makes it clear you don't care about the subject. You just want solutions handed to you. If you wanted to learn, you'd be reading a book first. Fuck you and fuck anyone who answers your shitty braindead homework questions. Go ask these in Chegg or Quora.
>>
>>14851921
Learning isn't just about sitting on a chair in a school classroom and looking at what an instructor's writing up on the board. It's about trying to understand things and figure out how to bring together anything applicable from what you already know to what you are currently trying to learn.
>>
>>14851955
Well to be fair I'm more interested in comp sci than math but I'm kinda interested in both.
>>14851962
Yeah I asked for a list of good books to read to gain a deeper understanding of math in the thread. I think I will get started on those
do these seem good to you

>Velleman, D.J. (1994). How to prove it.
Do everything.
>Montgomery, H.L., Niven, I., & Zuckerman, H.S.(1957). An introduction to the theory of numbers. AND Long, T.C. (1965). Elementary introduction to number theory.
Will help with writing proofs. Solve everything upto congruence. Then skip unless you find Number Theory interesting.
>Artin, M. (1991). Algebra.
Will help getting used to abstraction. Do as much as you can.
>Friedberg, S.H., Insel, A. J., & Spence, L.E. (1979). Linear algebra.
You should do the whole thing, will prepare you for multivariable analysis. Watch 3blue1brown's series on Linear Algebra first.
>Enderton, H.B. (1977). Elements of set theory.
Gives context to Analysis and most of modern mathematics.
>Steele, J. M. (2004). Cauchy-Schawrz master class.
Prerequisite for Calculus/Analysis.
>Amann, H., & Escher, J. (2005). Analysis.
Very difficult but comprehensive book on Analysis. Watch 3blue1brown's series on Calculus first.
>Abbott, S. (2000). Understanding analysis.
>>
>>14843727
Would I get more marks if I wrote "Thanks" in morse code at the end of the paper?
>>
>>14851989
You clearly are not ready for those.
https://4chan-science.fandom.com/wiki/Mathematics#Precalculus
>>
>>14851989
If you really just wanna pass Calculus I, go do a review of middle school and high school algebra and then go through a textbook on Differential Calculus (either Stewart or Larson).
You'll have to learn linear algebra later on (somewhere around second or third semester), but I don't think you'll ever have to take number theory or real analysis for CS.
In addition, you'll probably see proofs in Discrete Maths, which you'll most likely get in second semester, so don't worry too much about them for the meanwhile.
>>
>>14852017
thx anon, I'll look into it
>>
>>14851989
I made this list. I made it for a someone who has finished school and wants to pursue mathematics and improve their proof writing ability, not someone who doesn't know basic algebra. For a guy who just wants to code, Stewart's book and the other stuff in >>14852013 is fine.

>>14852017
>I don't think you'll ever have to take number theory or real analysis for CS
Is Number theory not like very important for CS? I guess it doesn't matter. He probably just wants to be a codemonkey and doesn't care about algorithms.

>>14852022
>I'll look into it
You will not.
>>
>>14852022
NTA, but i would like to give an extra recommendation, when i was highschooler and didn't know shit in calculus i was helped immensly by this playlist by Richard Delaware
After watching this i was able to get solid scores on my calc exams without even needing to read the book.
Richard Delaware also has a course on algebra playlist if you want to learn algebra (never watched it myself cause i never needed to)
Hope this helps you the same way it did to me.
>>
>>14852026
>Is Number theory not like very important for CS?
It's important for cryptography work, but most universities don't have it as a required course for CS majors.
>>
>>14852034
thx, I usually just use organic chem tutor, I like those kind of videos so hopefully this will help too
>>
>>14852034
The internet and its consequences had ruined math education for years to come.
>>
I'm trying to better understand the issue behind the divergence of $\frac{\hat{r}}{r^2}$
I understand there's some goofyness because of the hidden division by zero. I understand that, as the sole source in the entire vector field, it must be the source of all the divergence over the vector field. I also understand that the divergence is given by $4\pi \delta^3(\vec{r})$

What I don't understand is how/why the divergence apparently vanishes everywhere outside of the origin. Obviously, if you look at a graph of the vector field, the vectors continue to diverge outside of the origin, which means it should have a non-zero divergence. Saying it's because of the nature of the delta is just begging the question.
Obviously I'm misinterpreting something. Can any of you see what I'm missing?
>>
>>14852105
that should be $4\pi \delta(\vec{r})$. My bad.
>>
Anons, anything similar to this: [YouTube] ADHD Relief Music for Better Concentration and Focus, Study Music for Focus (embed) ?
Like constant looping beats. This helps me getting things done but I'm kinda getting tired of this one. Thanks
>>
>>14852122
>>
>>14852105
If you consider a point away from the origin and draw a small ball around that point you can see how some parts of the vector field are pointing out of the surface of the ball and others are pointing into it, so at that point it's not unreasonable that the divergence is zero
>>
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So why wouldn't this work?

Keep in mind that the amount of fissile uranium in the mix is a very small amount and the sphere has to spin pretty fast to push an appreciable amount of fissile uranium out of the solution. That way the envelope of non-fissile fluid can be very large relative to the chain zone and we can siphon heat away at a manageable rate.
>>
>>14852122
>>14852124
Its a bit different but I'd look into maplestory music

>>
How did physicists draw figures on their books before computer was a thing?
>>
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>>14852162
By hand. Then somebody else had to make an engraving or stamp of it.
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>>14852148
Thanks, anon
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How do I prove: $\forall a,b \geq 0 \quad a \leq b \iff a^2 \leq b^2$?
>>
>>14852208
Use square roots.
>>
>>14852208
Use logarithms.
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>>14852208
$a^2-b^2 = (a-b)(a+b)$
$a-b$ is negative since $a \leq 0$ and $a+b$ is positive, so $a^2-b^2 \leq 0$.
>>
>>14852208
using the mean value theorem of course
>>
>>14852237
>$a + b$ is positive
Proof?
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>>14852274
its the sum of positive numbers
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>>14852278
Yeah and?
>>
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How do you calculate the closure of an unclosable operator? Higher level math doesn't make any sense.
>>
>>14852337
Just because the operator doesn't extend all the way to $L^2$ that doesn't mean it has no non-trivial closure.
>>
>>14852337
>>14852360
Wait, no, that's not the issue, my bad.
Compute $\delta$'s closure as a subset of the graph $L_2 (0, 1) \times \mathbb{K}$
>>
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>>14852385
That does seem to be what the question is asking. This book here defines everything in terms of relations.
>>
If there are any engineering students,
Sorry for posting here, I may have accidentally chosen /relationships/ to ask my question by using that board
>>
>>14852688
>>14852034
try this?
>>
is this a good kick in the butt for programming motivation? or is this entirely invalid (as a layman)?
Letting your imagination take you to the work/project you are currently involved in or want to do: cognitive training.
By studying I become intelligent. Which increases my ability to problem solve. And that makes me healthier in attitude
and excelling towards my best interests. It makes me healthier by increasing my proficiency. By increasing my proficiency
I increase my competency. My competency is determined by my ability to do work. I am
determined and therefore competent because I am motivated and can learn the correct way to do things.
As I do the correct things, my skill is increased. My skill is valuable. Programming skills are very valuable. I value programming
because it increases my intelligence. My intelligence includes a skill set. The skill set is empirical, flexible, and sober,
and therefore scientific. (tense?) By practicing science I am thinking more clearly in all areas of life.
And the future may be more predictable and manageable due to science. I am fully able to use logic, troubleshooting,
and problem solving, for this productive paradigm. This view that I have through science of the world
is exceedingly proficient by implementation. By implementation I can be at the forefront
of this vast territory of technology. This technology enhances mine and other's lives in at every layer
in the world fractal of continuity, experience, and individuality. Learning is freedom in this evolving world. I am learning
everytime I innovate and unfold my experience with hands on programming. Innovating is helpful. I help my experience
by enjoying programming and socializing; I always take care of myself.
By validating and sharing work
1/2
>>
>>14852693
Thanks, I will definitely watch at least first few videos. I am already not unfamiliar with Algebra
As I said I am already familiar with Maths to some degree, and more worried about Physics I though
>>
2/2 this is intended as a hypnosis script or post suggestion. I want to know if this is a valid venture is all. I drafted it in a relaxed state without proper coming out of hypnosis.
I increase my prospects through a resume. I can create a resume, anytime. It's easy. I will show work on it. I
am happy progressing to my achievement and in doing so increase my confidence.
It's easy because you use internet resources to develop a resume, such as github, or obtaining certificates
which I steadily and stably work towards. The online pedagogy is streamlined while I make good decisions. I make good decisions
by staying stable, and, reflecting -critically-, on the choice of available material. I choose high information material and love
taking my time to read through the relevant bytes to my query.
I am therefore valuable as a confident, intelligent, skill builder capable of stimulating disciplined and
stable action towards an achievable outcome with a virtuous ethical paradigm, purely devoted to a better way of living.
>>
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>>14852716
What kind of physics are we talking?
There's DrPhysicsA, he does videos on most basic subjects and is more informative than your average youtube "physicist", i still would recommend using it in conjungtion with a textbook though

If you want textbook recommendations you can find plenty of those at the /sci/ wiki
https://4chan-science.fandom.com/wiki/Physics_Textbook_Recommendations
>>
>>14852713
>>14852717
this is 'drake'
i just wanted to lay claim for the responsibility...
and point out a few details.
1. it's really short.
2. athere are obvious doors you can open with this script, by afterwords working on /prog/ for several months, there are new avenues one can add to the script.
2. b this is just a constellated hyperbole of the act of /prog/. i do mean that it's a good kick in the butt, but this implies my own knowledge and what I've been led to believe about the subject.
3. lmao at the replies.
>>
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>>14852736
>What kind of physics are we talking?
Should be general physics all engineering students have to learn in freshman year, but I really don't know beyond that. In few years I will take advanced physic classes anyways, so anything I learn now should come handy later.
For now I only need to know as much as (not-so) "basic" high school physics as possible. I don't think I will learn everything as it's stuff people spend years studying but I am hoping DrPhysicsA-san will help me a bit
I will look into textbooks as I make progress, thanks about it
>>
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Why does x_3=x_3?
>>
>>14852778
They are writing the general solution in terms of x_3. Read what you just wrote again. Maybe several times until it smacks you in the face.
>>
How long can a 25 year old do meth every day before they die?
>>
>>14843727
If there is a sphere of fissile material whose rest mass is just below criticality, and it is accelerated to a fraction of c, would it go critical?
>>
>>14853145
going faster doesn't change the number of atoms in the material.
>>
>>14853159
no but it changes the amount of energy in the atom, why couldnt it take that extra energy and decay into decay products?
>>
>>14853163
it doesn't change the half-life of the atom
>>
Tell me useful tricks for writing a LaTeX document
>>
>>14853202
Practising and read tex.stackexchange is the only way.

But one universal tip is to put all your formatting stuff in your preamble while you main document should purely be about the contents. For example, you should not have commands like $\texttt{ \textbf, \mathbf, \mathbb, \centering, \hspace, \vspace}$. They should all be automated. If you want bold vectors, then declare a separate vector command which bolds symbols, if you want expectation, or R to be written in blackboard bold, make a separate command which displays blackboard E (preferably one that includes an argument which it puts in a bracket) and make a separate command for R which displays blackboard R. Don't include stuff like ad hoc vertical spacing below section headings, declare it in your preamble how you want your sections to be formatted. Sometimes ad hoc formatting is unavoidable, especially in table and math mode, but keep them to a minimum, to maintain a consistent clean look. This also allows you change your entire formatting very easily. For example, if you suddenly want your vectors or probabilities to be formatted a different way.

One most common ways you can make your document ugly is if you are messing with $\texttt{ \textheight}$ using the $\texttt{ geometry}$ geometry package. You will change this variable when you change the vertical margins. Use the option $\texttt{heightrounded}$ so that your interline spacing is an integral multiple of the $\texttt{ \textheight}$. This will allow the last line of every page to vertically aligned. In fact, if you are messing with any sort of vertical spacing, make sure to add enough stretchiness to allow it to be an integral multiple of $\texttt{ \baselineskip}$. I do this with $\texttt{ \displayskip}$ since I think the default separation between math and text is too much, but I add enough stretchiness to it such that it covers the original length.
>>
>>14853466
I mean so that your textheight is an integral multiple of interline spacing not the other way around.
>>
>>14843727
>>attach an image (animal images are ideal. Grab them from >>>/an/)

The whole thread is devoid of animals and is instead full of anime girls. You should update this link to point to a booru so people can get anime girls to post.
>>
>>14853202
\null is a very useful command when formatting, and it saved me multiple times.
>>
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>>14853469
I recommend using safebooru.org for work safety reasons
>>
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We got our big semester assignment yesterday.
Currently stuck on this one, could someone explain it to me? We haven't had the subject yet, since we got 2 months left to hand in this assignment, but I just want to be finished with it.

The task I am stuck on as part of the assignment is pic related.
>>
>>14853572
"One of each" includes two possibilities, these are when the first is crown and the second is coin and when the first is coin and the second is crown
So there are four possibilities, and each one of them is equally likely (assuming the coin is fair)

Think of it like this, when you roll a dice, there's fifty-fifty chance the number is even and a fifty-fifty chance the number is odd. But "being an even number" actually includes 3 possibilities, namely {2,4,6} and the same goes for "being an odd number"
>>
>>14853202
Some important formatting commands are:
\llap, \clap, \rlap, \smash
Math equivalents are available in mathtools packages.
Also: \phantom, \hphantom, \vphantom.
\mbox \makebox
>>
>>14853587
That makes sense. Is this applicable to any of the tasks though? Neat info to have in my head.
>>
1. What is the total entropy of two isolated systems?
2. What is the entropy of a single particle?
>And now for the actual question
3. When you take a gas, allow 1 particle to slip to another compartment, and then isolate both, what will be the total entropy?
>>
>>14853572
Crown, coin? What the fuck are you talking about? Is that some retarded British way of saying heads and tails?
>>
>>14853635
I'm going to put this into rigorous probability terms, not sure if your course includes this, but i believe it will make things more clear.
Whenever we have an "experiment" such as flipping n coins or rolling n die, etc. then we must define a sample space (often denoted by $\Omega$).
A sample space is a set which contains all the possible outcomes of the experiment
For example if i flip 2 coins then the sample space would be $\Omega = \{HH, HT, TH, TT\}$ where HT is the outcome that the first coin is heads and the second is tails, etc.
Subsets of $\Omega$ are called events, for example the event that the two coins give the same result can be represented by the subset $\{HH, TT\}$ and the event that the coins are different can be represented as $\{HT, TH\}$

Anne is basically trying to say that getting heads or tails on the first throw shouldn't affect the probability of getting heads or tails on the second throw but she seems unsure (in more concise terms we would say that the two throws are $independent$)

Bernt is even more confused than Anne, he seems to think that the events {HH}, {TT}, {HT, TH} have the same probability, whereas this is not the case (from the way we wrote it, it's obvious that the two events {HH}, {TT} have probability of 1/4 each and the event {HT, TH} has a probability of 1/2)
>>
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>>14853678
You know that other countries have other currencies..? But It's Norwegian, translated with DeepL.

>>14853682
> rigorous probability terms
I understood it clearly, thanks anon. Makes a lot of sense when you put it that way.
>>
>>14853671
1) $S = S_1 + S_2$ where $S_i = k_B \ln{\Omega_i}$

2) You can't define the entropy of a single particle in classical thermodynamics, though you can using quantum theory but that's a different microscopic entropy to what you are asking about.

3) Same as 1) but you've changed the $\Omega$ microstates of each by +/- 1 particle.
>>
>>14853709
What is happening on the gas side is clear: it lost a little bit of entropy. But now that that particle has been singled out, it cannot be assigned an entropy by 2). Yet, by the second law, we expect the total entropy to have gone up (or this process would not have happened). How can this make sense? My opinion is it cannot, and thermodynamics (indeed the second law itself) is not valid in this example. I'm curious of what others think.
>>
>>14853686
>translated with DeepL.
That explains why I was getting a stroke reading this.
>>
>>14853720
That law about entropy is only true for a closed system. By removing or adding a particle to each that is no longer true so it doesn't apply.
>>
>>14853720
NTA but you're correct, the second law is a statistical law not a fundamental law, it is not applicable to quantum and microscopic scales (to certain limits)

>>14853727
We can consider the two compartments as a closed system
>>
>>14853738
> We can consider the two compartments as a closed system
No you can't since they aren't in contact. You said it yourself, they are each isolated systems.
>>
>>14853738
>it is not applicable to quantum and microscopic scales (to certain limits)
I'm still trying to cope with this. It feels like a case of the Sorites paradox: how small can a system be before thermodynamics fails to be applicable, and how can this failure be measured?

>>14853749
You could say that two isolated systems are, taken together, another isolated system. But I get your point: the system as a whole should be isolated and allow for energy transfer of some sort. By the way, that's another thing that I rarely see properly enunciated: you need interactions or some other energy transfer mechanism throughout the system to get thermodynamics at all. And moreover this mechanism needs to occur on a small enough timescale. I don't buy the idea that thermodynamics is based on information theory at all, but if equilibrium takes infinitely long to reach, and once at equilibrium stuff moves so slow it might as well be frozen in place, applying thermodynamics doesn't make sense. In sum, there seems to still be a sizeable gap between the theory of thermodynamics and the systems that underpin it. If there is more to be said about this I'd love to hear it.
>>
Every quasiorder $R$ in $M$ induces an equivalence relation $S$ in $M$, such that for $a,b\in M$
$aSb \Leftrightarrow aRb \land bRa$.
Is this fact used anywhere?
>>
>>14853842
Thermodynamics is a macroscopic statistical theory. I don't know what gave you the idea it remains valid outside of the regime it was intended for.
>>
>>14853866
I didn't say it's valid outside of the macroscopic regime. I'm just feeling around to see what "macroscopic" means, and what happens when we tread the limit of what can be considered macroscopic. This isn't just particle number but also timescale of interactions. Have particles in a box with too great a volume, and the particles rarely ever interact anymore; therefore equilibrium may take arbitrarily long to establish, and hence thermodynamics cannot be applied. I guess what is ticking me off is that people talk about the heat death of the universe as the state of highest entropy (equivalently lowest free energy), when the whole concept of entropy cannot be applied to the universe as a whole because of the reason above. Or would you disagree?
>>
>>14853842
>I'm still trying to cope with this.
The second law is only applicable to large systems, and i'll admit how we define "large" is somewhat arbitrary.
This is the case because at the quantum scale all elementary processes are reversible (an elementary particle can gain energy just as easily as it can lose it for example), it is only through the interaction of many particles do irreversible processes emerge due to statistical and probabilistic laws.
If you're still confused then try reading section 6 of chapter 2 of 'An Introduction to Thermal Physics' by Daniel V. Schroeder
>>
>>14853469
Do as I say, not as I do.
Anime images randomly make people seethe and call me a tranny groomer pedo and whatever the fuck. Animal images are universally beloved.
>>
>>14853955
>Anime images randomly make people seethe
All the more reasons to post anime images then
>>
Need help with this: Give an example of a subset of the complex plane that does not have any interior point and is unbounded.
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>>14854080
Are you serious?
$\mathbb{Z}$ works for example.
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>>14850972
good news bros
I got my grade back and it was an 83 so I got a low B
It said plus extra credit, so what I assumed happened was I got a bad grade but a bunch of others got an even worse one so I got a curve
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>>14854104
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>>14854136
They both work.
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>>14854141
Why does R work?
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>>14854145
Because it's unbounded and has no interior point.
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>>14854145
because every point is a boundary point, and boundary points can't be interior points
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How do you get to that using 2.4?
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>>14854192
Since $x < q^{p + 1}$ we have that $\alpha_p q^p \leq x < q^{p + 1}$ immediately implies $\alpha_p < q$.
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>>14854210
thank you very much
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>>14854146
>>14854148
What? Isn't every point in IR an interior point?
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>>14854342
Take any real number x and any radius r > 0. Then the open ball around x with radius r will contain non-real complex numbers like for example x + i r/2
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>>14853682
I am back anon, appreciate the help.
So in task d), isn't the probabilities the ones you listed or am I confused? Is there a way to visualize probabilities with the Omega?

and for e) what are some probability terms you can tie to this?
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>>14843727
so im an autist that has difficult time understanding human emotion sometimes so im going ask a basic human question here

So i was having conversation with another classmate and he said he was a comp sci major, then he asked what my major was.

i told him im an electrical engineering major. After that he shut the conversation short and walked away
what did i do wrong here? I feel like we were having a decent time conversing
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>>14854585
Are you sure that's all there was to the conversation?
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>>14854210
oh, I've got another small question: $\alpha_p$ is only defined to not be 0 or equal to anything less than 0 in this case, right? As in, solely per the Archimedian principle, it'd be an element of $\mathbb{Z}$?
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>>14854586
yes that's all there was. I didnt raise my voice or come off arrogant. I always try to go for a humble approach in all things.
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>>14854585
Could be that the guy is an asshole. In any case, just approach him and ask him why. If he's not a cunt, he'll feel bad for making you feel bad.
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>>14854585
just humbly ask him. If he doesnt tell you its just that he is a complete asshole. If he tells you then there you have it
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>>14854585
>he shut the conversation short
did he? how? if you're truly autistic that could just be your misconception or misreading.
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>>14854585
From my extensive knowledge of human interaction, there are three major possibilities in my head:
>he actually wanted help with homework or whatever and realized you couldn't provide it
>he figured out he had run out of conversation subjects and cut the conversation short
>the way you answered him signaled to him that you wanted to stop talking
The last one doesn't imply you're more autistic than you thought, normies do that shit on accident all the time.
>>14854601
Well yes. The text literally states $\alpha_p \in \mathbb{N}$
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I have calc1 mid-term coming up and we're getting questions from chain rule, power rule, product/ quotient, and implicit differentiation.
My professor didn't give many tutorial questions and told us to find questions ourselves. He didn't conduct two lectures because he got sick and did 3 lectures in one day, 2 weeks before midterms.

Would it be enough to do Stewart's and Larson's chapters on these topics to git gud.
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>>14854660
>he actually wanted help with homework or whatever and realized you couldn't provide it
>he figured out he had run out of conversation subjects and cut the conversation short
both very good points. where a normie might react with 'what a dick' someone of a more sensitive nature would go 'oh no, what did I do wrong? everyone hates me'
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>>14854660
I see that. I just wanted to make sure it doesn't come from $q>1$.
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>>14854606
>>14854608
bad advice. you'll come off as clingy and annoying. Fuck them normies, anon.
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>>14854656
nah he just said okay and turned the other way
>>14854660

>he figured out he had run out of conversation subjects and cut the conversation short

this is the most likely i think. The only other possibility that you didnt list is that he's insecure and thinks i "outrank"
him in someway. Should have mentioned that too many people at my school are too overly competitive. Which i funny because i go to school because i want genuinely knowledge.
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>>14854690
>him in someway. Should have mentioned that too many people at my school are too overly competitive. Which is funny because i go to school because i genuinely want knowledge.

jesus christ i cant seem to write properly today. i meant to write: Which is funny because i go to school because i genuinely want knowledge.
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is sex immoral?
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If we have to prove a conclusion from a bunch of statenents, and the conclusion is of the form a->b, are we allowed to assume a is true?

(A v B) -> (C & D)
(D v E) -> F

Therefore A -> F

I can assume A along with the other 2 premises right?
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>>14854725
only if you have a kid that you cannot support/ or give the best quality of life
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>>14854736
It's not clear what you're asking.
Is E supposed to be C?

It sounds like the answer will be no.

>Either way, doing dancing or soccer, I'll lose weight. (D or S)->W
>I'll definately either sign up for dancing or for soccer, (D or S)
>I'll lose weight.

We concluded W, but we don't know if D or S is the reason.
It works to derive W because we postulated the conjunction.

>I met a guy who form the look of it is either from Japan or China.
>Either way, he speaks a tongue I don't understand.
We conclude something about the guy without knowing where he's from. It's just that both conjuncts have the same implication.
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>>14854474
>So in task d), isn't the probabilities the ones you listed or am I confused?
Yes, 1/2 for "one-of-each" 1/4 for two tails and 1/4 for two heads
This is of course assuming the coin is fair (chance of landing heads is the same as landing tails)
>Is there a way to visualize probabilities with the Omega?
Try using set diagrams like picrel? it's completely up to you how you choose to visualize it as long as the drawing is clear.
>what are some probability terms you can tie to this?
IDK, this question probably must be put in the context of what you already learned, but i guess independence can be tied to this problem because the throws were independent. But more importantly we used the term "event" to describe certain subsets of Omega, for a fair coin the probability of an event is equal to the number of elements in the event divided by the number of elements in Omega

You may want to check this pdf if you have problems understanding basic probability
https://www.sydney.edu.au/content/dam/students/documents/mathematics-learning-centre/introduction-to-probability-theory.pdf
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>>14854758
Like:
Premise 1: (A v B) --> (C & D)
Premise 2: (D v E) --> F
Conclusion: A --> F

I don't see a way to prove A-->F is true from the given premises without also being able to assume A is true.

Is this how you solve it, by assuming A is true (counting it as a premise)?
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Is there a word equivalent to cranial for the torso? Like, a cranial stabbing vs, like a torsular stabbing? Whatever the real word is.
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>>14854777
pectoral? proximal?
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>>14854772
Premise 1: (A v B) --> (C & D)
Break up the conditional: [A --> (C & D)] & [B --> (C & D)]
Take the first proposition: A --> (C & D)
Break it up again: (A --> C) & (A --> D)
Take the second proposition: A --> D
Add a disjunction to it: A --> (D v E)
Premise 2: (D v E) --> F
Hypothetical syllogism: A --> F

The logical manipulations above have names but i forgot what they're called, i only remember the hypothetical syllogism
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>>14854787
proximal will work, thanks
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How long would it take to learn math Algebra 1 -> Calculus 1 (Inclusive), assuming I dedicate 3 hours/day to rigorous study?

I graduated high school 4 years ago, and work full time as an electrician.
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>>14854835
A week
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>>14854690
>The only other possibility that you didnt list is that he's insecure and thinks i "outrank" him in someway.
Honestly that sounds like you're projecting your autism and I can't actually picture real people acting like that but you do you.
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>>14854877
could be. But i genuinely believe competition turns people back into apes. like they genuinely believe hardwork magically entitles them to something
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so im supposed to differentiate these problems.

for this one should distribute the 4 and the 2 before taking the derivative?
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>>14854813
I don't think disjunction is legal in that step, I think it would have to be (A-->D) V E

I don't think you can use rules of inference on a sub part of the statement
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>>14854916
Now i think about, i could've broken premise 2 into (D --> F) & (E --> F) then use D --> F to prove A --> F
That wouldn't require introducing a disjunction
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>>14844647
The first equation is wrong because you're assuming that the node connecting the 1 ohm and voltage source is 60V. This would be the case if the voltage source is directly grounded, but (assuming that the node connecting the current source, 50 ohm, and 4 ohm is ground) it's not because of the 4 ohm resistor. As for the second equation, I honestly don't know how they got it, But it does lead to the correct result. Regardless, now knowing that the voltage isn't tied directly to ground, you should be able to the nodal analysis and get 65V.
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can I live on protein shakes, rice and multivitamins?
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I want to plot some curves in the complex plane. Is there a tool that's particularly good that this? I could use a basic graphing utility, but then I have to parametrize my curve or convert to (x,y) coordinates and sometimes that's not very feasible.
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>>14854667
bump
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>>14854835
A few months.
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hey bros how do you pay attention and remember what you learn in class? i like forget it while im doing homework and have to look back at my notes. then before an exam i like have to completely reteach it to myself...
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>>14853571
>Cauchy
>Koishi
That doesn't make sense. Koishi has a diphthong whereas Cauchy has a monophthong.
>>14854667
Going through the entire problem sets for those topics in either one of those books would be more than what I did to pass Diff. Calculus.
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>>14855159
I take notes off the textbook a week before seeing the topic in class, and then I review them (or practice exercises related to them) every day until the next topic comes up.
I got this study tip from an eroge btw.
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>>14855086
You could live off potatoes and cheese if you want to.
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>>14843727
Can you see Andromeda with the naked eye without a scope on the best viewing conditions on Earth, and does it resemble an elliptical shape like a galaxy?
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>>14855337
>i am too lazy and pretentious to bother going outside to look at the sky myself, instead i'll ask the internet if what i'm planning to lie about having seen in the sky is a plausible lie
ridiculously image conscious poser, but also too low iq to be capable of pulling off the charade effectively.
why are these two characteristics so commonly comorbid, is there a scientific explanation?
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>>14855361
What the fuck. It's below freezing here and I live in Bortle scale 5 light conditions. I ask out of curiosity because I think it would be incredible to look up and see a galaxy so large and clear in the sky, instead of having to use a scope. I have seen it with a cheap monocular. No need to be a toxic moron.
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>>14854762
Took me a while to answer, sorry. Really appreciate the help anon and I will look into the pdf you linked, seems to hit the nail on the head with what I need.
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Any idea on how do I do this exercise (induction)?
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>>14856725
First check that's true for n=0 then show that
[eqn] \frac{1-x^{n+1}}{1-x} + x^{n+1} = \frac{1 - x^{n+2}}{1-x}[/eqn]
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>>14856733
thank u
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Let $S \subset \mathbb{N}$ be the set $\{n_1,\ n_2,\ n_3,\ ...\}$ where $n_k <n_{k+1}.$
How do I show if $s \in S,$ there exists $m \in \mathbb{N}$ such that $n_m = s$?
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I posted this on /fit/ but I think here is probably a better place to ask.
How to regain focus, /sci/? My attention span is very short, every time I try to study something it seems that I can only focus for like 20~30mins, how should I go about fixing this? I guess meditation could be a good start or some sort of "dopamine detox", but how long would it take to become normal?
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>>14856813
*Nonempty set, sorry
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>>14856813
What?
If there is no such $m$ then $n_a \neq s$ for all $a \in \mathbb{N}$ hence $s \notin S$ which is a contradiction
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>>14856813
Abstract the statement away to "For any sets $A, B$ let $f: A \to B$. Prove that $b \in Im \ f \iff \exists a \in A : f(a) = b$", in which case you're being asked to prove the definition.
You can also argue from the total order on the natural numbers if you want to be cheeky.
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>if only a finite number of digits are retained in the $q$-ary expression of $x$, then the absolute error of the resulting approximation of $x$ does not exceed one unit in the last rank retained
I don't get it
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>>14856870
actually, I think I get it now. Feel free to reply, though, if you're sure about it.
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>>14856828
> 20-30 minutes
Depends on how intensive those 20-30 minutes are. If you are intensely writing/reading for that period of time, most people start to get tired and need a break. If it's mostly slacking, ehh..

As for me, It's just one simple method, routine, routine and routine. It's the only thing I must FORCE myself to accept in my daily life, because I know if my routine goes to shit, so goes my motivation/focus/studies etc.
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How would I go about achieving this? Can I just gradually crimp the blue pipe where the purple arrow is pointing until the flow is split?
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Reading through a psychology paper and I'm trying to figure out what CR 2.14 or CR 1.56 means. It's comparing the change in response between two different age groups. Does it mean change ratio?
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>>14857206
post paper, this isn't enough information
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Why isn't the denominator of the second derivative not written as (dx)^2
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>>14857380
But it is?
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>>14854889
i want to know if im wrong ree
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Would someone mind checking my work? I'm supposed to calculate the flux out of this hemisphere (r=4, quadrants 6 and 7) using the divergence theorem for the vector $\vec{F}= yx^2\hat{i} + (xy^2-3z^4)\hat{j} + (x^3+y^2)\hat{k}$
however, when working the triple integral in spherical coordinates, I get a problematic term that cancels the flux to 0

$\nabla\cdot\vec{F} = 2xy+2xy+0$
$\iint_S \vec{F}\cdot dS = \iiint_V \nabla\cdot\vec{F} dV \Rightarrow 4\iiint_V xydV$
converting to spherical coordinates, where $\phi$ is the angle from the z axis,
$4\iiint_V xydV = 4\int_{\frac{\pi}{2}}^{\pi} \int_{\frac{-\pi}{2}}^{\frac{\pi}{2}} \int_{0}^{4}(\rho sin(\phi)cos(\theta)\cdot \rho sin(\phi)sin(\theta))\cdot \rho^2sin(\phi)d\rho d\theta d\phi$
$= 4\int_{\frac{\pi}{2}}^{\pi} \int_{\frac{-\pi}{2}}^{\frac{\pi}{2}} \int_{0}^{4} \rho^4 sin^3(\phi)cos(\theta)sin(\theta)d\rho d\theta d\phi$
evaluating,
$= \frac{4}{5}\int_{\frac{\pi}{2}}^{\pi} \int_{\frac{-\pi}{2}}^{\frac{\pi}{2}} (\rho^5 sin^3(\phi)cos(\theta)sin(\theta))\bigg\rvert_{\rho=0}^{\rho=4}d\theta d\phi$
$= \frac{4096}{5}\int_{\frac{\pi}{2}}^{\pi} \int_{\frac{-\pi}{2}}^{\frac{\pi}{2}}sin^3(\phi)cos(\theta)sin(\theta)d\theta d\phi$

evaluating theta is where I get an issue: $\int_{\frac{-\pi}{2}}^{\frac{\pi}{2}} sin(\theta)cos(\theta)d\theta = 0$
which cancels the entire expression out. Where am I going wrong?
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>>14857682
>using $[\pi/2, \pi]$ as a range for $\phi$
Fucking why?
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>>14857712
because the sphere section is defined from the x-y plane down to the -z axis, so w.r.t. the +z axis, the angles would be pi/2 to pi
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>>14843727
Any help with the sum in pic? Using residues and computing [eqn]\sum \rightarrow\oint _C dz \frac{e^{iz\zeta}}{z^2+\phi}[/eqn] i get:
[eqn]\frac{\pi}{\sqrt{\phi}}\left) e^{-\sqrt{\phi}\zeta}- e^{\sqrt{\phi}\zeta}\right)[/eqn]
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>>14857792
left(
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>>14857792
I can't tell what you mean by "using residues and computing sum -> oint (...)", but since the left hand is a Fourier sum in xi, the natural way to get there is backwards: compute the Fourier coefficients of the left-hand side.
Alternatively, you could use the series to prove that the series s(xi) satisfies $s''(\xi)=\phi s(\xi)$, then find the coefficients in the general solution by inserting convenient values of xi.
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>>14858053
sorry, I meant to compute the Fourier coefficients of the right-hand side, which should be pretty straightforward
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To prove this is a tautology, can i do proof by cases, and for each case do a proof by contradiction?
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>>14857637
I'm pretty sure everyone agrees that people sometimes feel as if working hard entitles them to things.
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>>14858124
it doesnt. Its a sad fact of life that not many people accept
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is vibrator a type of harmonic oscillator?
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how do I make my trans gf start programming? she doesn't want to even try
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>>14858053
>I can't tell what you mean by "using residues and computing sum -> oint (...)"

There is a theorem that says you can use the residue theorem for computing some series $\sum_n f(n)$ by finding a function that has poles in $\mathbb{Z}$. The way one does this is by using $g(z)=\cot(\pi z)$ which has poles at every $z\in \mathbb{Z}$ and the series is computed as:

[eqn]\sum_{n=-\infty}^{+\infty} f(n) = \frac{1}{2i}\oint _C dz f(z)\cot(\pi z) [/eqn]

In my initial solution i missed the cot part, but even with this i cant quite get it yet
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>>14844474
its said that the two topological spaces have the same underlying set.
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what if you posted rozen maiden images rather than touhou images?

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