/sqt/ /qtddtot/ - stupid questions thread

[Anonymous No.12637888]

Copy and paste edition

>what is /sqt/ for?
Questions regarding math and science, plus related advice requests.
>where do I go for other questions and (advice) requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt >>>/adv/ etc.
>how do I post math symbols (Latex)?
https://imgur.com/MDiglsS.png
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
https://scholar.google.com/
>where can I look up if the question has already been asked here?
>>/sci/
https://boards.fireden.net/sci/
>how do I optimize an image losslessly?
https://trimage.org/
https://pnggauntlet.com/

>where can I get:
>books?
https://spoon.wiki/Books
https://stitz-zeager.com/
>articles?
sci-hub.st
>book recs?
https://sites.google.com/site/scienceandmathguide/
https://4chan-science.fandom.com/wiki//sci/_Wiki
http://math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>carreer advice?
https://sciencecareergeneral.neocities.org/
>help with calculus?
https://spoon.wiki/WolframAlpha
>charts?
https://imgur.com/a/JY6NNeL
https://imgur.com/a/0qDEgYt
>tables, properties and material selection?
https://www.engineeringtoolbox.com/
http://www.matweb.com/

General advice for asking questions here:
>attach an image (animal images are best. Grab them from >>>/an/)
>avoid replying to yourself
>ask anonymously
>remember to check the Latex with the Tex button on the posting box
>if someone replies to your question with a shitpost, ignore it
>avoid arguing with Yukarifag
>do not tell us you came from whatever the fuck board, /pol/ in particular
>do not mention how [other place] didn't answer your question so you're reposting it here
>If you use j for the complex unit, put a ¿ somewhere in your post or use emoticons I will automatically ignore your question. I don't actually know about everyone else, but you shouldn't assume they're too far off about whatever random things they dislike

[Anonymous No.12637893]

>>12637888
I don't think anyone really minds this, right.
But the /sci/ bump limit is 310, and /sqt/ usually still lasts ~12 hours after reaching the bump limit.

[Anonymous No.12637903]

>>12637888
Are there /sci/-approved climate change infodumps? I fall victim to conspiratorial thinking on occasion, and want teh scoop direct.

[Anonymous No.12637909]

Suppose I have N random variables drawn from a uniform distribution and denoted [math] X_1, X_2, ..., X_N[/math], where [math] N \sim Poisson(\lambda) [/math]. What the fuck is the unconditional probability, for [math] U = max(X_1, X_2, ..., X_N)[/math], that [math] U \le t[/math] for some [math] t \in (0,1)[/math]?

I'm a bit confused. Since each of the [math] X_i[/math] are drawn from a uniform distribution, the prob that some [math] t \ge U [/math] is [math] Nt^{N-1} [/math]. The marginal prob of the N is given, so I thought I could solve this using
[eqn] f(x|y) = f(x,y)/f_Y(y) \implies f(x|y)f_Y(y) = f(x,y) [/eqn] but numerical sims say that this isn't right. One's a discrete variable and one's continuous so I'm also not sure how to accommodate this since a pdf wouldn't make sense... I tried using an indicator variable to no avail.

pls help

[Anonymous No.12637921]

>>12637893
then stay there if you have unanswered questions/are reading. this is for anons who don't want to post a question and then not be able to get an answer because of bump limit

[Anonymous No.12637964]

>>12637909
[math]f(U|N)f(N)=f(U,N)[/math]
[math]f(U)=\sum_{n=0}^{\infty}f(U|N=n)f(N=n)[/math]

[Anonymous No.12637976]

>>12637964
and [math]P(U\leq t) = \int_0^tf(U)dU[/math]

[Anonymous No.12638009]

>>12637964
>>12637976
thanks babygirl

[Anonymous No.12638036]

>>12638009
y-you forgot no homo right??

[Anonymous No.12638831]

>>12638036
;)

[Anonymous No.12639257]

How many Anki's do you guys do a day? I do 100 a day and review other 100.
It's making me tired bros

[Anonymous No.12639391]

>>12639257
learning nip, i do 6 and review about 20

[Anonymous No.12639458]

Help a retard understand these rational roots. Please.

[Anonymous No.12639497]

>>12637888
Anyone has tips for beginner publisher killer? I scanned couple books at the library using the special super expensive shit with all the bells and whistles, but it took way too much work and time before I could upload it to libgen.
I also borrowed a couple of books I wanted to upload, but the library is closed for at least another month. What should I look for in a budget scanner for this particular use? It's a borrow and I can't just tear the binding, so built-in curvature correction? Or is doing it in software postprocessing good enough?

[Anonymous No.12639614]

meme or based?

[Anonymous No.12639634]

>>12639614
total meme, has been discussed many times

[Anonymous No.12639638]

also, this one, meme or based?

[Anonymous No.12639641]

>>12639634
ok, thanks

[Anonymous No.12639659]

>>12639638
Obviously a meme made in five minutes.
But you can still do it. inb4 filtered retards whining about how "Spivak hard I lost half of my friends to a Spivak class."

[Anonymous No.12639668]

>>12639659
how would you learn calculus + linear algebra then?

[Anonymous No.12640232]

besides getting a degree, what are the advantages of going to college to learn math rather than just reading on your own?

[Anonymous No.12640440]

>>12640232
Lectures, learning from a teacher, talking to fellow students etc.

[Anonymous No.12640453]

If "nature" is so "intelligent" then why it didn't gears ?

[Anonymous No.12640647]

Sorry for being a complete brainlet but can I get some math over how much mass gets converted into energy via nuclear fusion of the other isotopes of hydrogen?

I know that 4Hydrogen converts .7% of mass into energy. But what about the others?
Does Deuterium-Deuterium have a higher efficiency?

[Anonymous No.12640649]

>>12640453
It does. Most jumping insects uses gear mechanism for their long jumps

[Anonymous No.12640666]

Sorry for being a complete brainlet but can I get some math over how much mass gets converted into energy via nuclear fusion of the other isotopes of hydrogen?

I know that 4Hydrogen converts .7% of mass into energy. But what about the others?
Does Deuterium-Deuterium have a higher efficiency?

[Anonymous No.12640781]

>>12640666
It completely depends on the nuclei involved. The mass of the final nucleus for all elements up to iron is lower than the constituents due to the nuclear binding energy and that difference is released as energy. It's not something you can really use math to work out since you would need to calculate all the strong and weak interactions in the final nucleus which isn't feasible so in the end it's just a case of making measurements.

[Anonymous No.12640804]

>>12639458
1.

x^4-4x^3-x^2+16-12 = 0
1+16=17=12+4+1; so clearly x=1 is a root. Dividing the polynomial by x-1 gives
x^3-3x^2-4x+12 = 0
Convert to depressed form by setting x=u+1
(u+1)^3-3(u+1)^2-4(u+1)+12 = 0
(u^3+3u^2+3u+1)-3(u^2+2u+1)-4(u+1)+12 = 0
u^3 +3u-6u-4u +1-3-4+12 = 0
u^3 - 7u + 6 = 0
Clearly u=1 (=> x=2) is a root. Dividing the polynomial by x-2 gives
x^2-x-6 = 0
=> (x+2)(x-3) = 0
Overall: x^4-4x^3-x^2+16-12 = (x-1)(x-2)(x+2)(x-3)
=> roots are 1, 2, -2, 3.

[Anonymous No.12640832]

>>12639458
>>12640804
2.
4k^4-17k^2+4=0
All powers are even so this is just a quadratic in k^2. Put q=k^2
4q^2-17q+4=0
q^2-(17/4)q+1=0
Convert to depressed form with q=r+17/8
(r+17/8)^2-(17/4)(r+17/8)+1 = 0
(r^2+17r/4+289/64)-(17r/4+289/32)+1 = 0
r^2-289/64+64/64 = 0
r^2-225/64 = 0
r^2=(15/8)^2
r=±15/8
q={-15/8+17/8,15/8+17/8}={2/8, 32/8}={1/4,4}
k={±1/2,±2}
=> 4k^4-17k^2+4 = 4(k-2)(k+2)(k-1/2)(k+1/2)

[Anonymous No.12640854]

>>12639458
>>12640804
>>12640832
3.
x^4-2*x^3-3*x^2+8*x-4 = 0
1+8 = 9 = 2+3+4 => x=1 is a root
Dividing by x-1 gives
x^3-x^2-4x+4 = 0
1+4 = 5 = 1+4 => x=1 is (again) a root
Dividing by x-1 gives
x^2 - 4 = 0
=> (x+2)(x-2)=0
=> x^4-2*x^3-3*x^2+8*x-4 = (x-2)(x+2)(x-1)^2
roots are 1, 1, 2, -2

[Anonymous No.12640871]

>>12640781
No, no.
Just the hydrogen isotopes on the picture

Does 4 Hydrogen have the same efficiency as Deuterium + tritium? If so, how come the other have greater MeV released?

[Anonymous No.12641207]

So I read an article about Boötes Void - the largest void in the observable universe with an approx. diameter of 330 million lightyears. I stumbled upon this quote by an american astronomer and I‘m asking myself how this is even calculated?

I mean wouldn‘t we nevertheless be able to observe other galaxies despite being in the center of this supervoid? We would have had enough time to evolute on earth so light could have reached us much much earlier, right?

[Anonymous No.12641239]

>>12641207
popsci fags leave the board

[Anonymous No.12641240]

>>12641207
All he's saying is we didn't have the telescopes with enough resolution to resolve galaxies over 330m light years away until the 1960's.

[Anonymous No.12641377]

>>12634114
thanks anon.
but he's dead.
also, i had a flashback i was raped by him.

[Anonymous No.12641384]

>>12641377
alright check em'
(as a toddler)
myposts desu:
>>12633725
>>12633727

[Anonymous No.12641407]

any mathbros here? Have an exam in linear algebra tomorrow and most of people have Chegg accounts and hired people to solve it for them but I'm too much of a poorfag. will /sqt/ help me? I'm not a total retard and I can pass on my own but I'm afraid those cheating bastard will fuck up the average

[Anonymous No.12641457]

>>12641377
desecrate his tomb. If possible get the corpse and rape it/shit on it. This would give you some closure I guess

[Anonymous No.12641463]

>>12641407
we do not help people cheating. If you have a question, ask it without stating that you're a cheating pleb who just studied enough to barely pass and fear the curve.

[Anonymous No.12641489]

>>12641463
its not like that, I already scored 40/50 in my mid exams, I'm good at the first part of the subject but pretty shit at last chapters mainly because the teacher was teaching them in a hurry

[Anonymous No.12641499]

>>12641463
/sqt/ has a proud tradition of helping cheaters cheat so long as they're funny, likeable lads.
This lad isn't really either so I don't actually care about him tho.

[Anonymous No.12641538]

Given object A and object B. You can get object B by adding new properties to object A. How would you call such a relation?

[Anonymous No.12641943]

>>12641457
not possible


cremated

[Anonymous No.12641965]

>>12641407
>>12641489
just ask the question without giving any context and you will get answer

[Anonymous No.12641984]

Can someone explain why this happens?

[Anonymous No.12642024]

>>12641984
[eqn]e^{\frac{1}{x}\log{(a)}} - 1 \sim_{x \to \infty} \frac{1}{x} \log{(a)} [/eqn]

[Anonymous No.12642186]

>>12641538
Depends on the context I guess, math physics chem what field are we talking?

[Anonymous No.12642209]

When taking [math]\int\delta(t-t_o) s(t)dt[/math] The answer I expect is s(t_0) but then when I use wolfram alpha to compute [math]\int_0^2\{pi R}\delta(t-t_o) e^{frac{-ikx}{R}}dt[/math] I get a function that relies on heavyside functions. Does chaning the limits of integration change the way delta works in an integral?

[Anonymous No.12642218]

>>12642209
am i just dumb, should i be specifying that a is smaller than 2piR.

[Anonymous No.12642238]

>>12642186
Field is IT and its about two JSON files LOL.

[Anonymous No.12642244]

i got a zero percent on a quiz because our book didn't use the term "fundamental frequency" and our instructor never defined it, so I didn't know what it was.

our book used the terms "fundamental mode" and frequency of the first harmonic, in hindsight i should've assumed this meant frequency of the fundamental mode or first harmonic of course, but i wasn't sure and it wasn't even in the books index

i asked my teacher for clarification, hoping i'd get some sort of points back due to an undefined term being used but just got kind of a condescending reply telling me it was defined (a search of the pdf also reveals the term is never used). shit bugs mang

[Anonymous No.12642248]

>>12642209
[eqn]\int_a^b \delta(x-k) f(x) \, dx = \begin{cases} f(k), & a \leq k \leq b \\ 0, & \text {otherwise} \end{cases}[/eqn]
I suspect that the Heaviside functions are just a convoluted way of making it zero if a is outside the limits.

[Anonymous No.12642275]

>>12641984
[math]\lim_{x \to \infty}\frac{a^{1/x}-1}{x^{-1}}=\frac{0}{0} [/math]
[math]\lim_{x \to \infty}\frac{e^{\ln(a)1/x}}{x^{-1}} \underbrace{=}_{Hospital}=\lim_{x \to \infty}\frac{-\frac{\ln(a)e^{\ln(a)1/x}}{x^2}}{-x^{-2}} = \lim_{x \to \infty} \ln(a)a^{1/x}=\ln(a)[/math]

[Anonymous No.12642345]

>How many bits required to represent 256 numbers?
I don't understand the question. I just don't.

[Anonymous No.12642378]

>>12642345
look at binary, the question is asked badly and should say how many bits to represent numbers from 0-256 i assume.

[Anonymous No.12642386]

>>12642238
I guess just use modify?

[Anonymous No.12642408]

How do I deal with an undefined element in a sum, [eqn]\sum \frac{1}{x}[\eqn] my first instinct is to just ignore [math]n=0[\math] but that strictly changes the question.

[Anonymous No.12642412]

>>12642378
8bits? 1 byte?

[Anonymous No.12642438]

>>12642408
What are you summing over?

[Anonymous No.12642468]

>>12642438
some range that contain 0, from -a to b. I dont really care about the answer just how to deal with the incontinuity

[Anonymous No.12642557]

>>12642468
Be more specific; are you integrating or is this a discrete sum? Finite or infinite?

[Anonymous No.12642605]

How... do I start solving this? I've done some really goofy calculus manipulation that I'm almost certain is incorrect

[Anonymous No.12642610]

How... do I start solving this? I've done some really goofy calculus manipulation that I'm almost certain is incorrect and there's nowhere for me to check what the right answer might be

[Anonymous No.12642617]

>>12642345
8 bits. 2^8 = 256. More generally, n=8 is the least n such that 2^n >= 256. If you have 8 bits, you can assign a distinct bit pattern to each member of a set with 256 or fewer elements.

>>12642378
> how many bits to represent numbers from 0-256 i assume.
0...256 is 257 numbers. 0...255 is 256 numbers. -128...127 is also 256 numbers. It doesn't say *which* numbers because it doesn't matter, only that there are 256 of them.

[Anonymous No.12642620]

>>12642610
2 coulombs. E=V*I*Δt, Q=I*Δt = E/V = 24J/12V = 2C. "Volts" is literally just joules per coulomb (or watts per ampere; W/A=(J/S)/(C/S)=J/C).

[Anonymous No.12642630]

>>12642620
Oh great, that's actually what I got with my retard equations somehow. Thank you.

[Anonymous No.12642676]

What's a good book for scientific computing in python?

[Anonymous No.12642952]

>>12642557
It's a Fourier series, but my coefficients have a constant factor of k^{-1} so it would be from -inf to inf

[Anonymous No.12643035]

In how many different orders can a couple produce 9 children with 5 boys so that a boy comes first and all 4 girls are born consecutively?
I interpret this as 4 girls must be preceded by a boy. I treat this as 'one thing' and hence apply the formula [math]P(5;1,4)=5[/math]. Is this correct?

[Anonymous No.12643161]

>>12643035
No need for the formula:
BFFFFBBBB
BBFFFFBBB
BBBFFFFBB
BBBBFFFFB
BBBBBFFFF

5 times. Another way: the first B can be ignored. The F set behaves as a singular element. Therefore you have the set (F,B,B,B,B). thus 5!/4!=5 because B is repeated.

[Anonymous No.12643389]

Any recommendations for resources on the mathematical foundations of statistical mechanics? I've wanted to go through Khinchin for a while now, but I wanted to see if there are other good resources as well.

[Anonymous No.12643395]

>>12643161
thanks

[Anonymous No.12643401]

Realistically, what does it take to get into the nuclear engineering program at a place like UC Berkeley?

[Anonymous No.12643589]

Test:
We know how to count: 1, 2, 3, 4, etc.
For every [math]a[/math], [math]b[/math], [math]c[/math] [math]\in\mathbb{R}[/math]:
[math](a+b)+c=a+(b+c)[/math].
[math](ab)c=a(bc)[/math].
[math]a+b=b+a[/math].
[math]ab=ba[/math].
[math]a(b+c)=ab+ac[/math].
There exists [math]\mathit{0}[/math] such that for every [math]a\in\mathbb{R}[/math]:
[math]a+\textit{0}=a[/math].
There exists [math]\mathit{1}[/math] such that for every [math]a\in \mathbb{R}[/math]:
[math]\textit{1}a=a[/math].
For every [math]x\in\mathbb{R}[/math] there exists [math]y\in\mathbb{R}[/math] such that:
[math]x+y=\mathit{0}[/math].
For every [math]x \in\mathbb{R}^{\times}[/math] there exists [math]y\in \mathbb{R}^{\times}[/math] such that:
[math]xy=\mathit{1}[/math].
[math]\textit{0}\not\in\mathbb{R}^{+}[/math]
For every [math]a\in\mathbb{R}[/math] either [math]a\in\mathbb{R}^{+}[/math] or [math]-a\in\mathbb{R}^{+}[/math], but not both.
For every [math]a,b\in\mathbb{R}^{+}[/math]:
[math]a+b\in\mathbb{R}^{+}[/math].
[math]ab\in\mathbb{R}^{+}[/math].

For [math]a_{n} [/math], [math]a_{k}\in\mathbb{R} [/math] and [math]N, M [/math] counting numbers.
As definitions: [math]\sum_{n=1}^{0}a_{n}=\textit{0} [/math], [math]\sum_{n=1}^{1}a_{n}=a_{1} [/math] and

[eqn] \sum_{n=1}^{N+1}a_{n}=\left(\sum_{n=1}^{N}a_{n}\right)+a_{N+1}. [/eqn]

Also as definitions: [math]\prod_{n=1}^{0}a_{n}=\textit{1} [/math], [math]\prod_{n=1}^{1}a_{n}=a_{1} [/math] and

[eqn] \prod_{n=1}^{N+1}a_{n}=\left(\prod_{n=1}^{N}a_{n}\right)a_{N+1}. [/eqn]

As theorems:

[eqn] \sum_{n=1}^{N+M}a_{n}=\sum_{n=1}^{N}a_{n}+\sum_{n=N+1}^{N+M}a_{n}. [/eqn]

[eqn] \prod_{n=1}^{N+M}a_{n}=\left(\prod_{n=1}^{N}a_{n}\right)\left(\prod_{n=N+1}^{N+M}a_{n}\right). [/eqn]

For every [math] \sigma\in\textrm{S}_{N} [/math]:

[eqn] \sum_{n=1}^{N}a_{\sigma(n)}=\sum_{n=1}^{N}a_{n}. [/eqn]

[eqn] \prod_{n=1}^{N}a_{\sigma(n)}=\prod_{n=1}^{N}a_{n}. [/eqn]

[eqn] \left(\sum_{n=1}^{N}a_{n}\right)\left(\sum_{k=1}^{M}b_{k}\right)=\sum_{n, k}a_{n}b_{k}. [/eqn]

[Anonymous No.12643598]

Test 2:
For [math]a_{n} [/math], [math]a_{k}\in\mathbb{R} [/math] and [math]N, M [/math] counting numbers.
As definitions: [math]\sum_{n=1}^{0}a_{n}=\textit{0} [/math], [math]\sum_{n=1}^{1}a_{n}=a_{1} [/math] and
[eqn] \sum_{n=1}^{N+1}a_{n}=\left(\sum_{n=1}^{N}a_{n}\right)+a_{N+1}. [/eqn]
Also as definitions: [math]\prod_{n=1}^{0}a_{n}=\textit{1} [/math], [math]\prod_{n=1}^{1}a_{n}=a_{1} [/math] and
[eqn] \prod_{n=1}^{N+1}a_{n}=\left(\prod_{n=1}^{N}a_{n}\right)a_{N+1}. [/eqn]

As theorems:
[eqn] \sum_{n=1}^{N+M}a_{n}=\sum_{n=1}^{N}a_{n}+\sum_{n=N+1}^{N+M}a_{n}. [/eqn]
[eqn] \prod_{n=1}^{N+M}a_{n}=\left(\prod_{n=1}^{N}a_{n}\right)\left(\prod_{n=N+1}^{N+M}a_{n}\right). [/eqn]
For every [math] \sigma\in\textrm{S}_{N} [/math]:
[eqn] \sum_{n=1}^{N}a_{\sigma(n)}=\sum_{n=1}^{N}a_{n}. [/eqn]
[eqn] \prod_{n=1}^{N}a_{\sigma(n)}=\prod_{n=1}^{N}a_{n}. [/eqn]
[eqn] \left(\sum_{n=1}^{N}a_{n}\right)\left(\sum_{k=1}^{M}b_{k}\right)=\sum_{n, k}a_{n}b_{k}. [/eqn]

For [math] \textit{1}\in\mathbb{R} [/math]. As definition:
[math]\textit{2}=\textit{1}+\textit{1}[/math].
[math]\textit{3}=\textit{1}+\textit{1}+\textit{1}[/math].
[math]\textit{4}=\textit{1}+\textit{1}+\textit{1}+\textit{1}[/math].
et cetera.
As theorems: [math]\textit{2}+\textit{2}=\textit{4}[/math], [math]\textit{2}\times\textit{2}=\textit{4}[/math] and [math]\textit{2}a=a+a[/math]; confirming the known facts that 2+2=4 and 2*2=4.

[Anonymous No.12643640]

>>12643589
>>12643598
Stop pressing enter after closing the [/eqn] tag, it ruins the formating. "Theorem: [eqn]2+2=4[/eqn] Proof: Trivial and left to the reader."
NOT
"Theorem: [eqn]2+2=4[/eqn]
Proof: Trivial and left to the reader."

[Anonymous No.12643770]

>>12643640
>Proof: Trivial and left to the reader.
not really

[Anonymous No.12643793]

Anyone familiar with supercompact and tall cardinals? Apparently supercompact is supposed to be stronger than tall, but looking at the definitions I've been able to find they look like the exact same thing. Can anyone explain what I might be missing?

[Anonymous No.12643798]

Can you check your flammables cabinet right now and tell me if your acetaldehyde solution is separated like this? Mine’s past expiry but i’m not sure if this is a sign that its gone bad

[Anonymous No.12643806]

I have this vague memory of a differential equations teacher showing us how to turn a second order ODE that might be "problematic" into two first order ODEs. Basically for this homework problem I have to do that but in reverse: take two first order ODEs and turn them into a single second order ODE.

Anyone remember what I'm talking about? It's just a dumb trick I can't remember exactly how it goes. Obviously if you know how to do it in reverse, tell me, but I think I might be able to figure out just working the trick backwards

[Anonymous No.12643886]

>>12643770
[math]\mathit{2}+\mathit{2}=\mathit{4}[/math] is a theorem, where [math]\mathit{2}, \mathit{4} \in\mathbb{R}[/math]. Now something different happens with [math]2+2=4[/math] where 2 and 4 are simply counting numbers. It's not just a theorem because it isn't inferred from some logical theory (e.g. counting numbers are not just the Peano objects, for they existed before any formalisation).

[Anonymous No.12643908]

The equilibria are clearly just [math] P(t) = P = 0[/math] and [math] P = 100 [/math], but how is this system "autonomous" (time invariant) when it's input is literally time?

I don't know how to make a phase diagram for this, it's just a quadratic function.. And as for stability, 0 is unstable, 100 is stable?

[Anonymous No.12643915]

>>12643908
>but how is this system "autonomous" (time invariant) when it's input is literally time?
A time-invariant system has a time-dependent system function that is not a ~direct~ function of time

[Anonymous No.12643920]

>>12643886
I think a formal proof of basic addition requires a long treatment on logic. I just skimmed through principia mathematica and that's the feeling I got.

[Anonymous No.12644052]

>>12643806
If you have y’’ = f(y’,y;x), just define z =y’. Then you have two ODE’s, these being z’ = f(z,y;x) and y’ = z. Maybe you’re talking about something more complicated than that, but that’s at least a way to turn one second order ODE into two first order ones

[Nice No.12644054]

>>12637888
Quick add to the /sqt/ OP:
Use (math) \example (/math) instead of (math)\example(/math). For instance:
>([[math]^{?}\prime_{\setminus}[/math]])
>([[math] ^{?}\prime_{\setminus} [/math]])
The first failed as intended.
>>12644027

[Anonymous No.12644057]

>>12643908
As the above anon said, autonomous just means no EXPLICIT time dependence (i.e. you can have derivatives wrt time, but there are no t’s in any of the differential equations themselves). For phase diagram, plug in sample values of P and find the sign of dP/dt. If it’s positive, P will increase, if negative, it’ll decrease. I think convention is to draw a number line and mark out the equilibria on the number line, draw filled circles at points of stable equilibrium, open circles at unstable equilibria, and arrows pointing in the direction of flow between equilibria.

[Anonymous No.12644070]

>>12644054
See https://imgur.com/MDiglsS.png (in the OP).

[Nice No.12644095]

>>12644070
Maybe it is more spacing than needed (given 2000 char limit). A single space after the opening bracket and before the closing one should suffice.

[Anonymous No.12644124]

>>12644095
You sure?
[math] \sin\pi\sin\pi\sin\pi\sin\pi\sin\pi [/math]

[Anonymous No.12644129]

>>12644124
Hmmmm.
Neat.
Testing if \sin\pi hasn't been entirely patched.
[math]\sin\pi\sin\pi\sin\pi[/math]

[Anonymous No.12644134]

>>12644129
It has, fuck.
[math] ^{?}\prime_{\setminus}^{?}\prime_{\setminus}^{?}\prime_{\setminus} [/math]

[Anonymous No.12644144]

>>12644134
Well that doesn't work.
>>12644129
It has, fuck. Testing random shit.
[math] _aba^{?}\prime_{\setminus} [/math]

[Anonymous No.12644156]

>>12644134
Didn't work.
Anyhow, if you want to replace the current guide on the OP, you should just make a new guide image. The current advice might be overkill, but it still works.

[Anonymous No.12644159]

How would you explain
What are the possible values of a and b so that the equation √(6+a)=b is true
I think I have an idea but I don’t want to assume I’m right just to be wrong

[Anonymous No.12644305]

>>12643915
>>12644057
thanks, this kind of clicked after I posted. would you mind checking my thinking on pic rel? same scenario, just a different question.

>a)
obviously the equilibria are just a solution to the quadratic that's formed for the values of h. this is just shifting the curve up on the y-axis, so the stability for the first and second equilibria are still the same, unstable for the first, then stable for latter. so as h increases, the gap between equilibria seems to be decreasing.

>b)
there are no real equilibria here because the discriminate of the quadratic is negative, the curve is shifted below the t-axis. I'm not 100% sure what this means for the fish, do they go extinct?

>c)
this is just the quadratic we've been using the whole time:
[math] P = \frac{-0.005 \pm \sqrt{0.005^2 -4(0.5)h}}{2(0.5)}[/math]
>d)
I believe this amounts to just finding a value for the discriminant such that quadratic will equal zero. so according to the above, that should be when [math]0.005^2-4(0.5)(h)[/math] = 0, which occurs at 0.0000125. However, it looks like more like 12.5 on the graph. What am I doing wrong here?


other than d), did everything else sound rihgt?>

[Anonymous No.12644307]

>>12644305
>shifitng up on the y axis
shifting down,my bAD

[Anonymous No.12644314]

>>12644307
>>12644305
so pic rel is gives me the solution I need, 12.5. But where did the "HN" come from on the second equation? in my case N = 100, I don't see how it would distributed to H.....

[Anonymous No.12644316]

>>12644314
forgot pic FUG

[Anonymous No.12644350]

>>12639668
Depends on what you want to use calculus/linear algebra for, if it's more applied stuff then you can use more standard books. If you want to go into pure math it would be slightly different (well usually just a longer path).

[Anonymous No.12644372]

so this is a generated slope field for the stuff I was spamming above, it looks like without any harvesting, the population explodes asymptotically toward infinity. what about carrying capacity? am I doing this wrong?

[Anonymous No.12644386]

>>12644372
That equation looks like it's for a carrying capacity of 100, but your axes go from -30 (negatives make no sense for population) to 30. Try changing the vertical limits to be 0-200.

[Anonymous No.12644388]

Is there any video that explains the definition of limits of a sequence to a brainlet like me?

[Anonymous No.12644398]

>>12643389
Anyone?

[Anonymous No.12644403]

>>12644386
your right, realized right after so deleted. still stumped by my other question regarding 2d) here: >>12644305

[Anonymous No.12644429]

>>12644305
The problem is in c), you've got 0.5 where you should have 0.005 and vice versa

[Anonymous No.12644452]

>>12644429
why would that be the case? in the quadratic, b = 0.005, and a=0.005*100 = 0.5

[Anonymous No.12644458]

>>12644429
you're right though, i mean it results in the right answer when I flip them around in the discriminant. wtf is going on?!?!

[Anonymous No.12644470]

>>12644458
>>12644452
>>12644429
oH mY GAAAAWWWD I was mixing up my A's and B's

HHHUUUUUgulkauhf;safhs;he

[Anonymous No.12644476]

Are there any bacteria that won't cause any problems and can make my colon bioluminescent so I can leave glowing turds?

[Anonymous No.12644488]

stable or an unstable bitch? i said unstable cuz it would be hard to put a marble on it without it falling off

[Anonymous No.12644507]

ok, last question (literally). I don't really get this, as my quadratic wasn't in this form, if I let B=1 it's essentially of the same form, but equality doesn't hold like it should on the last line.

[Anonymous No.12644509]

>>12644507
forgot pic. i also just don't understand the question, why am I solving for something I supposedly already have?

[Anonymous No.12644521]

>>12644476
There are safe bacteria in live yogurt and sauerkraut, and putting bioluminescence genes into stuff has been done for a lot of species with genetic engineering, I think you could probably make those method work on those bacteria. I think it involves making a virus that puts the genes into the target organism. The bacteria might just evolve away the genes since they wouldn't be contributing to their fitness and bacteria evolve faster than larger organisms, also they wouldn't necessarily take over your colon from the species already there unless you wiped those out with antibiotics or something. Please note that I am not a doctor, antibiotics have side effects, and viruses can make you sick.

[Anonymous No.12644642]

>>12643908
An autonomous system is invariant under a shift along the axis corresponding to the independent variable. So if f(t) is a solution, then so is g(t)=f(t+t0). This is why you need initial conditions to get a specific solution. Models of physical systems are usually autonomous as a consequence of the laws of physics not changing from day to day. Whether you run the experiment today or tomorrow, you get the same result up to a shift in the time axis.

[Anonymous No.12644718]

>>12644488
It's semi-stable. dP/dt is zero at P=50 and negative either side. If you increase P to 50+δ, dP/dt is negative so P will decrease back toward P=50. If you decrease P to 50-δ, dP/dt is negative so P will decrease further away from P=50. I.e. it's stable on one side and unstable on the other.

More generally, P is an equilibrium point when dP/dt=0, it's stable if d(dP/dt)/dP<0, unstable if >0, semi-stable (probably) if =0 (technically this requires the second derivative w.r.t. P to be non-zero, i.e. the first derivative changes sign at the equilibrium point).

[Anonymous No.12644805]

>>12641538
well A is general and B is a special case of A (because more properties, so less general)

[Anonymous No.12644840]

Lads I'm fucking retarded. I'm trying to understand this Diophantus riddle for myself. I'm obviously missing some elementary understanding of how the algebra breaks down for the final solution. I can understand up to:
x = 75x/84 + 9
but not sure how it breaks down from there.
Another website had the next step written like
Hence 9x/84 = 9 or x/84 = 1. So x = 84
How do they arrive at this?

[Anonymous No.12644938]

>>12644840
> D = D/6 + D/12 + D/7 + 5 + D/2 + 4
=> D = 14D/84+7D/84+12D/84 + 42D/84 + 9
=> 84D/84 = 75D/84 + 9
=> 9D/84 = 9
=> D = 84*9/9 = 84
More generally, x=ax+b => x-ax=b => (1-a)x=b => x=b/(1-a).

[Anonymous No.12644954]

>>12644938
I guess it's basic highschool stuff. I have trouble remembering the rules for these simplifications. Probably it's just a matter of doing them over and over again and hoping then to not forget them.

[Anonymous No.12645309]

what is a2?

[Anonymous No.12645558]

>3 letters of recommendation
>These should be written by recommenders best qualified to speak to your academic progress, research skills, and potential for graduate study. Recommenders should submit their letters using the online application site.
is having more than 3 bad in any shape or way?

[Anonymous No.12645599]

I was thinking of something and came up with this problem.

I and J are areas.
x, A, and B are lengths.
I=J
Solve for x.

It turns in to some gradeschool algebra/geometry problem but I get stumped at the end.

[Anonymous No.12645672]

>>12645599
Let [math] \theta = \arctan(\frac{B}{A}) [/math].
Then we see that the height of the smaller triangle is [math] \tan(\theta)x [/math], and by your condition on the area [math] \frac{AB}{2} = x^2 \tan(\theta)[/math]. From there you can just solve for x trivially, discarding the negative solution.

[Anonymous No.12645680]

>>12645672
fuck meant [math]\frac{AB}{2} = \frac{x^2\tan(\theta)}{2} [/math]

[Anonymous No.12645729]

>>12645672
Wow I was doing x^2*B/2A=(xB/A+B)(a-x)/2 [equation of triangle and equation of trapazoid] Guess I need to relearn geometry.

[Anonymous No.12645755]

>>12645729
Well that solution is just as valid, it's just more yucky to deal with. It's easier to compare the area of the whole triangle (AB/2) with two times the area of the smaller triangle.

[Anonymous No.12645979]

Hello, I need help with this very simple probability problem. If P(A) <= P(B) then A belongs to B, is this true or false?

Please answer me fast. Thanks

[Anonymous No.12645994]

>>12645979
not necessarily

[Anonymous No.12645995]

What miner don't infect my computer with virus?

before asking, i have free internet and energy

[Anonymous No.12646033]

>>12645995
Maybe you should be asking that question on /g/ for more technical and appropriate answers.

[Anonymous No.12646068]

>>12645979
Not always. Consider a two coin toss, and the events (one heads, one tails) & (two heads).

[Anonymous No.12646101]

Explain how instrumental variables work and why they work like I'm 5. I already know the formal part but I want the intuition.

[Anonymous No.12646153]

>>12645599
It's probably easier to add a fourth variable y for the height of the vertical dividing line, along with the equation y/x = B/A => y=xB/A

I=J => xy/2 = (A-x)(B+y)/2
=> xy = (A-x)(B+y)
substitute y=xB/A
=> x^2(B/A) = (A-x)(B+xB/A) = B(A-x)(1+x/A)
multiply by A/B
=> x^2 = (A-x)(A+x) = A^2-x^2
=> 2x^2=A^2
=> x = A/√2 (the negative solution is discarded)

[Anonymous No.12646301]

>>12646276
The percentage symbol % means 1/100, think of a percentage like 23% meaning 23 × 1/100. So when you multiply a number x by y percent you're just calculating xy/100.

[Anonymous No.12646316]

>>12646301
thank you, but that is not what i had in mind. i mean if i have 10k dollars, and i choose to invest in x stocks with 1% gain each time, how many stocks would that have to be theoretically to reach 20k?

[Anonymous No.12646325]

>>12646316
10000*1.01^t=20000

[Anonymous No.12646377]

Is the delta function without a signifying magnitude still usable. For example do I say [eqn]s =a+\delta[/eqn] or [eqn]s=a+b\delta[/eqn].

[Anonymous No.12646390]

>>12646377
[eqn]s=a+\delta(x-x_0)[/eqn] or [eqn]s=a+b\delta(x-x_0)[/eqn]

[Anonymous No.12646414]

>>12646390
either is fine, at least in controls [math] \delta(t-t_0) [/math] is understood to be a unit impulse, i.e. [math] \int_{t_0-\epsilon}^{t_0+\epsilon} f(t)\delta(t-t_0) dt = f(t_0) [/math]

[Anonymous No.12646469]

>>12646377
While not intuitive, it means two different things. For example
[math]g_{\delta}(x)=a\delta(x-x_0), f_{\delta}(x)=-a\delta(x+x_0)[/math]
[math]\int_{\mathbb{R}}(g_{\delta}(x)+f_{\delta}(x))dx=a-a=0 [/math]
So specifying magnitudes has a meaning.

[Anonymous No.12646473]

I'm sorry I know I am really really retarded but how is this limit not just 1?
As x approach infinity 1/x goes to 0 so parenthesis goes to 1. 1 to infinity not just 1?

[Anonymous No.12646484]

I need to find a substitution so that

[math]dx \left( y^2 \sinh{x} - \frac{2(y^{'}(x))^2}{\sinh{x}} \right) = du \left( y^2 - 2(y^{'}(u))^2 \right)[/math]

So what is [math]u[/math] ?

[Anonymous No.12646493]

>>12646484
you seem smart can u explain >>12646473
to me please. Beating myself up over it

[Anonymous No.12646499]

>>12646473
[eqn]\left(1-\frac{1}{x}\right)^x = e^{x\text{ln}(1-\frac{1}{x})} \sim_{x \to \infty} e^{-\frac{1}{x}x} = \frac{1}{e}[/eqn]

[Anonymous No.12646506]

>>12646473
because you're still raising it to the x power. An easy way to think about it is to consider the cross terms, although as x -> infty 1/x^x goes to 0, you have an infinite amount of cross terms that fuck with your intuitive result.

[Anonymous No.12646521]

>>12646506
>>12646499
Thank you guys, it just clicked. I appreciate you help and sorry for spamming thread; cramming before test.

[Anonymous No.12646565]

>>12645599

[math] xh=2h(A-x)+(A-x)(B-h) [/math]
[math] AB=xh+2h(A-x)+(A-x)(B-h) [/math]

[math] AB=2xh [/math]
[math] AB/(2x)=h [/math]

[math] \frac{xh}{(A-x)}=h+B [/math]

[math] \frac{AB}{2(A-x)}=AB/(2x)+B [/math]

[math] 2xAB=(AB+2Bx)2(A-x) [/math]

[math] 2xAB=(AB+2Bx)(2A-2x) [/math]

[math] 2xAB=2A^2B-2ABx+4ABx-4Bx^2 [/math]

[math] 0=2A^2B-4Bx^2 [/math]

[math] x^2=A^2/2 [/math]

[Anonymous No.12646582]

>>12645558
Probably. Usually when you're applying somewhere online, the application form will ask you to input a given number of email addresses. If you ask for more than 3, your other referees won't be able to send their letter. They might not appreciate you making them write a letter they'll end up not sending.

[Anonymous No.12646628]

If you cuff each of a man's hands to the corresponding ankle, is there anything he can do to escape or harm anyone?

[Anonymous No.12646630]

>>12646628
he's at the perfect height to headbutt the groin

[Anonymous No.12646643]

>>12646630
Oh shit.
Any ideas on how we could solve this? Ideally he should still be able to walk.

[Anonymous No.12646749]

>>12646643
I'm pretty sure this would violate some geneva convention on torture, being placed in a stress position for transport or confinement. That being said if you place a solid bar, thats short enough, between the ankles he wont be able to move at any appreciable speed.

[Anonymous No.12646785]

>>12646628
>>12646643
MODS

[Anonymous No.12646814]

>>12646749
Hm, interesting. That should do, thanks.

[Anonymous No.12646856]

I'm finishing up a BSc. in Applied Mathematics. Should I get an MSc. in Mathematics or an MSc. in Statistics? Or what Master's degree should I get instead?

[Anonymous No.12646892]

Is zero part of the complex number line?

[Anonymous No.12646934]

>>12646892
yes

[Anonymous No.12648086]

what can you apply statistics to in the natural/physical sciences? where and why are statistics relevant?
of these applications, which are:
- useful for a beginner to experiment with
- useful for getting a job?

[Anonymous No.12648135]

Could a desert planet like tattooine or dune be real? If yes, would it still have groundwater?

[Anonymous No.12648142]

>>12648086
science is 100% statistics, which is why there is no truth in science.

Logic is just a field by autistic pedants about well formed formulas and valuations, ie a map sending a formula to 1 or 0 and asking what are those valuations which are stable under inference rules. Zero truth in this, especially truth in the casual sense. Tarski truth is moronic, meaningless. Peak atheist. Just like there is no truth in science, just some stats and a stat convention for saying ‘’if p value is XXX then the result is """"""""""""""’true"""""""""""


At best scientists can come up about some stats about some formal system (ie a model) like ''the spring'' or ''harmonic oscillator'' or ''the standard model''. Like ‘’your material has such and wear and tear, and our backlog of such conditions lead to 60% of breaking in the next year, therefore your material may break or not within a year’’ That’s the pinnacle of the scientific claim and all their claims remain phrased as uncertainty.

[Anonymous No.12648145]

>>12648086
Condensed matter is mostly statistical physics.

[Anonymous No.12648701]

>>12637888
Started the book 'Elements of Propulsion' yesterday and I'm having a hard time with the questions, this one with the thrust equation in particular bothers me since I can't see what I've done wrong (though so far I'm assuming it to be something to do with unit conversions);
>Use eqn. F = (m0+ mf)Ve - m0V0 + (Pe = P0)Ae
>10200 = 8200Ve - 0 + 14.696 x (164 x 3600) to convert Ae from lbm/s to lbm/h
>10200 = 8200Ve + 8676518 (-)
>-8666318 = 8200Ve
>Ve = -8666318/10200 = -849...
>Answer is 1973ft/s.
I'm confused as heck... can you convert both m to ft and s to hr in the same question? Will that make it right? I've always been put off of doing stuff like that.

[Anonymous No.12648768]

>>12648701
I see now that lbf = pound-force and lbm = pound-metre though I still don't understand where I'm going wrong? This should work, shouldn't it?!

[Anonymous No.12648785]

>>12637888
What software would I use for the first years of a Maths degree? I want to get a laptop but I'm not sure if I should get a W10/Linux one or if I can get away with a Chromebook.

[Anonymous No.12648842]

>>12646856
bumping

[Anonymous No.12649126]

>>12648086
All of modern science,i.e those based on quantum mechanics, is statistical in nature. Stats play a critical role in any scientific discipline today.

[Anonymous No.12649223]

what was used as the name for the unit of force before 1948? did they just use kg*m*s-2?

[Anonymous No.12649286]

if fast-moving objects are more massive than slow-moving objects, does that mean more massive objects are moving faster through time than less massive ones?

[Anonymous No.12649291]

and a follow-up: if massive objects create "gravity wells" through spacetime, doesn't this mean time in the space between massive objects moves faster, and is thus inherently massive?
Wouldn't this explain dark matter?

[Anonymous No.12649347]

>>12649286
A fast moving object isn't heavier in the strictest sense. It's total energy is it's rest mass, which doesn't change, and it's relativistic momentum. More energy does mean more gravity (curvature in GR).

Also fast moving objects, or heavier, are seen to have *slower* clocks when measured by a stationary observer not faster.

[Anonymous No.12649496]

>>12643793
Ok, found the difference, a single letter difference. Where supercompact has [math]M^\theta \subset M[/math], tall has [math]M^\kappa \subset M[/math].

[Anonymous No.12649611]

>>12648785
I've used Gentoo throughout my undergrad

[Anonymous No.12649692]

>>12648768
> I see now that lbf = pound-force and lbm = pound-metre
lbf = pound force, lbm = pound mass. Weight vs mass. 1 lbf = 4.448222 N (newtons), 1 lbm = 0.45359237 kg.

[Anonymous No.12649698]

>>12649223
No. Historically there have been many units of force but I'm not sure what were the most commonly used.

[Anonymous No.12649755]

>>12637888
Am I finally being exposed as a midwit?
I'm taking a classical mechanics course this semester and part of what we're doing is Lagrangian Mechanics.
Is this one of those things where you really need to work with it for a while to 'get it' or am I finally being filtered. I've never had this issue before, it's literally like a new language.

[Anonymous No.12649817]

>>12649755
> it's literally like a new language.
because it is. no one does Lagrangian or Hamiltonian mechanics until they leave school. until then everyone's experience is only with Newton so that is the only way they know how things can be done.

just think of Lagrangian Mechanics as a different way of writing the maths describing the state of the system but in the end you still get the same equations of motion you would with Newton. yes it is more complicated initially but it is also more powerful hence why most modern theories such as the Standard Model are written that way.

[Anonymous No.12649854]

>>12649817
So it's normal feeling like a complete retard when first starting off?
We're doing Hamiltonian later too, how different is it to Lagrangian? If I were to put in serious work (which I'm doing either way because its the final year of my bachelor), how alien would Hamiltonian be when we finally get there?

[Anonymous No.12649871]

>>12649854
The real midwit exposing act is asking questions that you know the answer to.

[Anonymous No.12649878]

>>12649854
> So it's normal feeling like a complete retard when first starting off?
Yes especially since most lecturers aren't great at explaining it. The Susskind book on mechanics and his YT lectures are some of the best I've come across.

Once you've grasped Lagrangian's then Hamiltonian's are trivial after that. It's useful since standard quantum mechanics and operators use that representation.

[Anonymous No.12649881]

>>12649755
Its a new way of approaching physical systems. Its a very good primer for QM in my opinion. It takes a while to get used too but once you do theres literally no reason to ever use Newtonian formalism again.

[Anonymous No.12649913]

>>12649878
I'll take a look, thanks.
I've dabbled in QM (intro class, first four-ish chapters of Griffiths), but we never made it a point to really understand/talk about the Hamiltonian.
>>12649881
Well atleast theres that.

[Anonymous No.12649931]

Let [math](X,\mathcal{A}), (Y,\mathcal{B})[/math] be measurable spaces. Suppose [math]\mathcal{E},\mathcal{F}[/math] generate [math]\mathcal{A},\mathcal{B}[/math] respectively. Let [math]A\in\mathcal{A}, B\in\mathcal{B}[/math]. How can I show that [math]A \times B \in \sigma({\{ E \times Y \}}_{E \in \mathcal{E}} \cup {\{ X \times F \}}_{F \in \mathcal{F}})[/math]?

Usually when asked to prove statements of the form "Show that property [math]\mathbf{P}[/math] holds for all sets in [math]\sigma(\mathcal{G})[/math]", I take the following approach: "Let [math]\Sigma = \{E \in \sigma(\mathcal{G}) : \mathbf{P}(E) \textrm{ holds}\}[/math], then it suffices to prove that [math]\Sigma[/math] is a sigma algebra and [math]\mathcal{G} \subset \Sigma[/math]". However I'm not sure how to apply this technique in the above setting.

[Anonymous No.12649954]

Can someone with Aspergers, suspect that they have it?

[Anonymous No.12649966]

Please tell me I'm going to be okay for the 5 classes + 1 lab I'm taking this semester starting tomorrow. I've never taken so many classes before despite being a junior.
I'm stressed.
I'm not going to make it, am I?
It's 3 math classes and 3 engineering classes. I have a decent amount of friends spread across the 6 classes but a part of me feels worried. I know that this might just be the pre-semester hyper stress thing that most students go through.
Any tips/advice? I can't drop because all of them are vital fundamental classes.
Happy webm to keep myself a bit sane.

[Anonymous No.12649987]

>>12649692
Ah, sorry for my mistake, I meant to write lbm, strange though, the conversion I saw between them was pic related and I tried to convert airflow and fuel flow both to lbf/h... I still haven't got the answer. Its really frustrating to be this retarded.

[Anonymous No.12650041]

>>12649913
Hang in there anon, I had the same exact experience taking upper division physics. It pays off dividends in the long run, especially if you plan to continue pursuing physics in graduate school. The Lagrangian and Hamiltonian formalisms are standard bread and butter.

[Anonymous No.12650045]

Hi I've got an inorganic chemistry exercise on the following couple of cobalt complex [math][Co^{III}(CN)_6]^{3-} / [Co^{II}(CN)_6]^{4-}[/math]
Basically we have to compare its reduction potential to Co3+/Co2+
I find that Co3+/Co2+ is a much more powerful oxidizer while the complex a more powerful reducing agent.
We are asked to explain this, based on the nature of the ligand. I figured that since cyanide is an anionic ligand it would reduce the cobalt's attraction to electron but I'm unsure. Anyone has an idea?

[Anonymous No.12650054]

>>12649966
plan ahead, go to office hours, you'll probably be fine. I'm on the quarter system so I dunno how bad 6 classes is for a semester.

[Anonymous No.12650076]

>>12649931
There is no trickery, it's a straightforward constructive proof.
I'll throw you a bone and remind you that [math]\sigma({\{ E \times Y \}}_{E \in \mathcal{E}} \cup {\{ X \times F \}}_{F \in \mathcal{F}})[/math] isn't the same as [math] \sigma({\{ E \times Y \cup X \times F \}}_{E \in \mathcal{E}, F \in \mathcal{F}})[/math]

[Anonymous No.12650077]

Are there any tips you can give to someone who's always comparing to someone else?
When I'm taking calc, and some guy knows the answer instantly and I don't, I beat myself up for it...
I think it might just be the competitive nature of STEM but is there any way to minimize it?

[Anonymous No.12650100]

>>12649954
Don't see why not, their problem is communication not introspection. But it's one thing to know what's wrong and another to solve it. Some of them do manage to learn to better hide their power level (though someone who pays attention will probably always be able to tell).

[Anonymous No.12650106]

>>12650100
thanks.

[Anonymous No.12650108]

>>12650077
Set your own goals / expectations which are defined independent of the performance of others. This means goals based on grades are usually automatically ineligible, since most classes have some sort of curve or other. For example, I'm happy when I think I've sufficiently learned X material that I care about, when I can do Y task, etc.
also >>>/adv/

[Anonymous No.12650283]

Opinion on Neurobics?

[Anonymous No.12650328]

Working with boolean algebra right now. How do I deal with 1 in my expressions?
For example
[math]x=A'B+A'BC'+A'BCD+A'BC'D'E[/math]
[math]x=A'B\left(1+C'+CD+C'D'E\right)[/math]
The correct answer is apparently A'B, but I'm not sure if the law [math]X+1=1[/math] for the entire parentheses expression is valid.

Is that what you're supposed to do?

[Anonymous No.12650357]

>>12650328
If the 1 is inside the expression and it's in operation with OR, then everything inside that parenthesis does not matter because anything that is 1 OR X is just 1. I don't know why the fuck this is a gif but look at rules 2 and 4.

[Anonymous No.12650378]

I am quite terrible at mental math, and the pace at which I complete my problems suffers as a consequence.

I have been trying to improve upon it by learning little tricks here and there, and I have noticed that for some problems I am able to just look at the numbers, and seemingly without thinking, know the answer immediately. This does not happen a lot though, but it's beginning to happen a little more often.

Are some of you peeps who have been challenging yourself for years have this aspect about yourself? Maybe to the degree where you feel like you are in autopilot mode whenever it comes to completing the calculations that a problem requires?

I would love to get to the point where I am committing almost all of my thought to the underlying problem itself and not to the intermediate arithmetic and algebra within the problem.

[Anonymous No.12650874]

Where is a good place to post statistical studies I do on my own?
I asked this in a previous thread and someone said Tumblr but there must be a better option

[Anonymous No.12650910]

>>12650874
your own website, a blog
tumblr is fine

[Anonymous No.12650951]

Im struggling so much with analysis I,
can someone help me prove [math] \mid x\mid*x^n [/math] is differentiable on R ?
Dont really need a full proof just not sure where to start

[Anonymous No.12650954]

>>12650951
I'd start by breaking that into a piecewise function, absolute values are annoying to deal with. Can you see where to go from there?

[Anonymous No.12650968]

>>12650954
I think so, thanks :)

[Anonymous No.12651043]

is the average of a product equal to the product of the averages? [eqn]<ab>=<a><b>[/eqn]

[Anonymous No.12651050]

>>12651043
Only true if the covariance of a and b is 0.

[Anonymous No.12651506]

what language is this?
https://www.youtube.com/watch?v=kcuiI3cvEVI

[Anonymous No.12651611]

>>12637888
what's the probability of randomly choosing a real number larger than x, where x is a real number?

[Anonymous No.12651648]

>>12651611
statistically certain

[Anonymous No.12651652]

>>12651611
50%

[Anonymous No.12651654]

>>12651648
then what's the probability of randomly choosing a real number smaller than x, where x is a real number?
how can both be certain?
my guess would be .5 but I'm not a maths guy

[Anonymous No.12651658]

>>12651652
can you explain your reasoning please? thank you

[Anonymous No.12651667]

>>12651658
there are just as many real numbers greater than x as there are real numbers smaller than x
imagine a number line, but centered at x. how many numbers are to the left of x? how many to the right?

[Anonymous No.12651671]

>>12651667
yeah that's what I was thinking too. just wanted to see if that was valid or just irrational
thanks

[Anonymous No.12651774]

So can someone point me into the right direction as to what the equation for modulating and demodulating an FM signal is?

[Anonymous No.12651972]

How come inflation doesn't cause orbits to grow?
If the distance between everything increases, with velocities remaining the same, shouldn't that cause orbits to grow exponentially and often even escape?

[Anonymous No.12652022]

what is the difference between a nuclide and an isotope?

[Anonymous No.12652030]

>>12651972
Because it's too small. If it can't prevent the Andromeda Galaxy 2.5m light years away being attracted to the Milky Way due to gravity then it's essentially zero inside our galaxy let alone the solar system. It is an effect that is only meaningful on the scale of hundreds of millions of light years or larger.

[Anonymous No.12652033]

>>12651774
[eqn]y(t)=A \cos(2 \pi (f_c\,t + f_\Delta \int_0^t x(\tau) \, d \tau))[/eqn]
You can't really describe demodulation algebraically. For a start, the signal you're dealing with isn't y(t) but a band-limited version with arbitrary amplitude and added noise. A formula which worked for a "perfect" FM signal wouldn't be of any use for a real FM signal.

[Anonymous No.12652040]

>>12652022
Isotope is more general as it applies to both elements and chemicals. Nuclide only applies to elements.

[Anonymous No.12652308]

>>12637888
Can anyone explain to me the relationship between the machine code of the program in the UNIX parent process and the machine code of the program in the child process when they are in memory?

[Anonymous No.12652319]

>>12652308
What are you asking specifically? They are both just data at different memory locations.

[Anonymous No.12652343]

>>12649826

[Anonymous No.12652453]

I need to learn High School physics very well in a month. I'm currently reading "University Physics with Modern Physics", it's pretty good but are there any resources that'll teach me faster?

[Anonymous No.12652495]

So I need help with math, I already flopped last year because I dont know high school math to be able to understand basic uni so any help? best resource?

[Anonymous No.12652533]

>>12652308
Each process has its own address space. Regions of that address space are mapped to either files or to virtual memory. The program code is in the code segments of the executables and shared libraries. As these segments are immutable (read-only), the mapping is shared, i.e. there will only be at most one copy of a given page in physical memory; all processes which have that page mapped will share the same physical memory page.

A child process is created by calling fork(), which clones the address space. Shared pages are shared, mutable pages are initially shared but set to copy-on-write (i.e. if any process writes to the page, it will be duplicated and the writing process gets a non-shared copy). Most of the time, fork() is closely followed by execve() to execute a different program, resulting in the existing mappings being discarded and new mappings being created from the new executable (and shared libraries).

[Anonymous No.12652678]

How to deal with flat earthers?

[Anonymous No.12652697]

Hello I'm a brainlet
How do I get into physics?

[Anonymous No.12652701]

Can someone explain why speed of light could be faster in one direction? It doesn't make sense to me because speed of light comes from permittivity and permeability of free space. Is there any evidence of magnetic or electric fields having different propagation speeds depending on the direction?

[Anonymous No.12652713]

>>12652678
Mostly ignore them, theres no reason to convince them otherwise. No flat earther is in a position to make important decisions. let them live with their delusions whats it to you?
>>12652697
You need a proper background in math. I'd suggest starting with Linear Algebra and Calculus and do Classical Mechanics alongside it. It should more or less show you what to expect.
>>12652701
No and thats the point theres no way to tell. Its the same as saying whenever you close your eyes you a pink elephant appears. Its just one of those hings that could be true or couldnt be true but theres no way to tell so we're restricted to what we can verify ably show, i.e the two way speed of light.

[Anonymous No.12652800]

>>12652697
brainlet is a relative term. define your brainletness

[Anonymous No.12652968]

>>12652713
The magnetic and electric field have the same speed independent of the direction of current.

[Anonymous No.12653093]

If a second order differential equation is homogenous, and the initial conditions are x(0) =0 and x'(0)=0, will the answer always just be y=0?

[Anonymous No.12653123]

>>12653093
Solve
[math]\frac{\partial^2 u}{\partial x^2}=cu[/math]
[math] u(0)=0, u'(0)=0[/math]

[Anonymous No.12653145]

>>12650054
It's more manageable in the semester system, but six is still a lot.

[Anonymous No.12653150]

>>12653123
I just got u(x) = 0 again.
With simultaneous equations A+B = 0 and √3A-√3B=0, the constants just = 0 right?

[Anonymous No.12653156]

>>12653150
Hint: consider the cases [math]c=0,c>0,c<0[/math]

[Anonymous No.12653160]

>>12653150
c not 3

[Anonymous No.12653241]

Is there a linear algebra textbook you like? I'm trying to start ahead.

[Anonymous No.12653245]

Let [math]\alpha_n, y_n > 0[/math] with [math]\sum_{n=1}^{\infty} \alpha_n < \infty[/math]. Define [math]F(x) = \sum_{n=1}^{\infty} \alpha_n \chi_{[y_n, \infty)} (x)[/math]. How can I show [math]F[/math] is almost-everywhere differentiable?

I believe that Lebesgue's differentiation theorem ought to play a part here but I don't really know how to begin. Any hint would be appreciated

[Anonymous No.12653250]

>>12653241
What level? Elementary or actual linear algebra? If it's the latter, then Shilov and Axler are two good complementary references imo.

[Anonymous No.12653271]

>>12653245
It's monotonic, hence a.e. differentiable.
Fixing up the eenie meenies of the proof is left as an exercise to you.

[Anonymous No.12653286]

>>12652533
thank you.

[Anonymous No.12653296]

How is the curvature of spacetime "distributed" among all the spacial and temporal dimensions?
In other words, would the physics theoretically allow situations where the spacetime curve manifests mostly in time rather than space?

[Anonymous No.12653314]

>>12653250
uhh, there's a difference? I just finished calculus 3...

[Anonymous No.12653340]

>>12653271
I wasn't aware of such a theorem (monotonic implies a.e. differentiable), but you're right, this sure gets the job done. I believe the problem can be solved without invoking said theorem simply because it was never mentioned in my MT class. But anyway, thank you anon

[Anonymous No.12653358]

>>12653314
Yes. You usually take an elementary linear algebra course after calculus 3, and that's focused mostly on matrix computations, like solving linear systems and diagonalization. They do introduce more abstract things like vector spaces, but that's not the focus.

An actual linear algebra course is proof based and uses more language from abstract algebra. Some topics covered include characteristic polynomials, canonical forms, inner products and more general bilinear forms, tensor products, to name a few.

[Anonymous No.12653463]

>>12653358
Ohhh, thank you!
I'll just have to find an elementary one then.

[Anonymous No.12653686]

Did the 2hufag leave?

[Anonymous No.12653766]

So, I want to know how to find out the dimensions and find basis for the following:
-in the element [math] f(x) of \mathcal{P}_3(\mathbb{R})[/math] the set of all those that satisfy [math] \int_{-1}^{1} f(x)dx [/math]
-From the set of n-order real square matrices, the subset of all symmetrical matrices (Those who satisfy [math] A = A^T[/math])
-From the set of n-order real square matrices, the subset of all alternating matrices (Those who satisfy [math] A = -A^T[/math])

How do I approach these? I can find basis for regular vectors and their dimensions, but in this case? (I know it must be basically the same, but I'm stupid)

[Anonymous No.12653811]

Is there a way i can visualize a complex function?

[Anonymous No.12653846]

>>12653811
You usually have to use level curves, either lines of z = u / z = iv or curves of equal modulus. In controls, you usually don't care as much about individual curves (outside of root locus stuff), but do indicate the poles and zeros of your function on the complex plane. If your function is rational, then usually the poles and the zeros are the most interesting features anyways.

If you mean visualize mentally, it's pretty damn hard since it's a 4D problem. Usually I like to think of a 3D plot of the modulus of the function, and then think of the arg as an independent 3D function, and try to combine the general trends of the two in my head.

[Anonymous No.12653882]

>>12653314
>>12653241
http://libgen.rs/book/index.php?md5=E54C542D5E57227A0380B0BFEE48972B

[Anonymous No.12654143]

I am currently an Applied Mathematics major. Is it worth changing my major to Statistics if I going to get a Master's Degree in Statistics anyway? The difference is that I can graduate in two years if I stay in the Applied Math program but I have to graduate in three years if I switch to Statistics. I want to look at careers such as Data Science and being a Quant bit I don't want to miss out on learning from relevant courses that I would have taken if I majored in Statistics.

[Anonymous No.12654160]

>>12654143
Also, to add on to this, let's assume that both programs take the same amount of time to complete. Is there a case made to stick with Applied Math over Statistics given my intention to study for a Master's in Statistics and my goal career in the field of Data Science?

[Anonymous No.12654181]

The university I graduated from 2 years ago just announced they're seeking creditor protection. The university is accredited. Is my degree worth nothing now? Is it time to panic? I work a good job based on said degree. I still want to go to grad school eventually.

[Anonymous No.12654203]

>>12653811
1. Take a rectangular or polar grid and draw its image or pre-image under the function.
2. Draw a 3d graph where height is the absolute value, and use hue to indicate the argument (angle).
Which is preferable depends upon what you're trying to visualise.

[Anonymous No.12654256]

>>12654181
Even if the university went bankrupt it doesn't invalidate the degree.

[Anonymous No.12654315]

I have a game involving two cointosses, each with a 15% chance to succeed plus 25 more on the second. The odds of at least one succeeding then is 1-((1-0.15)*(1-0.15-0.25))=49% I believe, but I would like to not phrase it as a bunch of subtraction. For something like "what are the odds of snake eyes" you can very easily say it's a sixth times a sixth. Is there a way to make the prior that elegant?

[Anonymous No.12654383]

>>12654315
There isn't really an "elegant" solution since your numbers, 0.15 & 0.4, don't have single english words to express them. If you want an expression without subtraction, you'd have to add up the probabilities for three events (HH, HT, TH), which isn't very elegant either since the two coins have different odds (and you'd have to do the subtraction anyways).

[Anonymous No.12654409]

>>12654256
Thanks for the reassurance anon.

[Anonymous No.12654472]

>>12654143
>>12654160
bump

[Anonymous No.12654504]

what are some most important things yo keep an eye on in a pediatric i.c.u.?
it's the time working with kids... and first time in rianimation center too... give me some advice please

[Anonymous No.12654644]

sin(2theta) = 4.9 = ?

[Anonymous No.12654698]

>>12654644
Assuming that you're trying to find theta, [math] | \sin(\theta) | \leq 1 [/math] for all [math] \theta \in \mathbb{R} [/math]. So, unless you copied down the problem wrong, you'd need to use the complex definition of [math] \sin(z) = \frac{e^{iz}-e^{-iz}}{2i} [/math] to answer the question.

[Anonymous No.12654869]

>>12654504
lmao anon if youre in that position you know more about that than any one here will. Dont fuck up and good luck

[Anonymous No.12655029]

>>12654504
maybe try asking /med/?

[Anonymous No.12655168]

[Anonymous No.12655199]

This is a solution to a problem in Atiyah-Macdonald's Introduction to Commutative Algebra. The hypothesis states that A is a Noetherian local ring, m is its maximal ideal and k its residue field. Also M is a finitely generated A-module.

This particular part asks to prove that if the mapping [math]\mathcal{m} \otimes M \longrightarrow A \otimes M[/math] is injective, then [math] \text{Tor}^{A}_{1} (k,M)= 0[/math]. I'm still just learning about the Tor functor and all that, but pic related is the proof I'm trying to understand, and my problem is that as far as I understand we would need a projective resolution to be able to find [math] \text{Tor}^{A}_{1} (k,M)= 0[/math] from its definition. It leads me to believe that I could somehow prove that m is projective, but is that possible?

[Anonymous No.12655616]

How the fuck do you find the roots of x^2 -3x -1 without using computers ?? Had this on a test but we never learned how to solve this without it being an easy equation to factor

[Anonymous No.12655662]

>>12655616
quadratic formula

[Anonymous No.12655751]

>>12655616
>not knowing the quadratic formula
you must be 18 years old to post on 4chan

[Anonymous No.12655753]

does anybody know of a database where I can find the radiated wavelength (""color"") of a lot of different atoms, molecules and compounds?

[Anonymous No.12655833]

>>12637888
How can I get better at Mental Math?

[Anonymous No.12655940]

>>12655029
ok sory

[Anonymous No.12656007]

>>12655753
https://www.nist.gov/pml/atomic-spectra-database

[Anonymous No.12656139]

>>12654472
if the app math major courses are too irrelevant you have to change major, especially if they involve little probability and computational aspects which are key in stats

[Anonymous No.12656188]

>>12637888
bros why im I so demotivated?
>2 months away from finishing undergrad
>classes im taking are bunch of extremely boring general engineering bs + a general elective + complex analysis and general topology
>feel completely and absolutely no drive to study at all
>cant even listen to class
>this is literally the final push and I feel like im not gonna make it out of sheer demotivation

what the fuck is going on? im hitting the gym, sleeping right, eating right, my relationship with my gf has never been better, WTF

[Anonymous No.12656192]

>>12655833
practice

[Anonymous No.12656196]

>>12656139
Well, looking in the courses in the course calendar, there are a bunch of courses that expand on Differential Equations and (computational) Linear Algebra and algorithms, not to mention that a few early year Statistics and Probability courses that I've already taken.

Do you suppose a Master's in Statistics would help fill in the gaps? The courses for an MSc in Statistics I'm interested in list courses such as those in pic related.

[Anonymous No.12656205]

>>12655833
Arthur Benjamin has a series of youtube videos about mental math techniques that are fun. You can also look up vedic math, which he covers a bit, but not completely. Thinks like modular division by 9 and 11 are easy ways to check your answer and be pretty sure it’s right. If you want to compute more complex operations like sine, cosine, log, fractional exponents, etc, you generally have to look up specific algorithms for each. All that said, mental math is a useless skill when you have a calculator in your pocket all day. If you want to learn it for fun, go for it, but it’s not going to give you an edge over your peers in math/science classes.

[Anonymous No.12656287]

>>12656007
Exactly what I needed, thanks bro.

[Anonymous No.12656327]

How the hell am I supposed to get to know professors so that they write me letters of recommendation for grad school?

[Anonymous No.12656338]

I was lurking on Jane Street's puzzle page.

>Jane received 78 figurines as gifts this holiday season: 12 drummers drumming, 11 pipers piping, 10 lords a-leaping, etc., down to 1 partridge in a pear tree. They are all mixed together in a big bag. She agrees with her friend Alex that this seems like too many figurines for one person to have, so she decides to give some of her figurines to Alex. Jane will uniformly randomly pull figurines out of the bag one at a time until she pulls out the partridge in a pear tree, and will give Alex all of the figurines she pulled out of the bag (except the partridge, that’s Jane’s favorite).

>If n is the maximum number of any one type of ornament that Alex gets, what is the expected value of n, to seven significant figures?

Is it like this for 12 drummers?

(12/78 + 11/77 ••• 1/67 + 1/66) * 12

And add the expected values for the others? Like so?

1.0661464026874792 * 12 +

0.9000262438147766 * 11 +

0.7488381093122021 * 10 +

0.6123622192142031 * 9 +

0.49038517213167127 * 8 +

0.3826996714288671 * 7 +

0.2891042668584125 * 6 +

0.20940311057830888 * 5 +

0.1434057265636213 * 4 +

0.09092679250573989 * 3 +

0.05178593336488073 * 2

= 46.0272819619

~ 46.02728 (7 sig. fig)?

[Anonymous No.12656342]

>>12656338
Wow, I'm sorry for the insane formatting. Mobile posting sucks and I keep getting directed to an ad page.

[Anonymous No.12656377]

>>12656338
You should be able to tell that your logic is wrong based on how you got a number substantially larger than 12.

[Anonymous No.12656382]

>>12656327
be the only competent and earnest student at a mid-tier uni

[Anonymous No.12656396]

>>12656196
bumping

[Anonymous No.12656398]

>>12656377
Initially I thought it’s (12/78 + 11/77 ••• 1/67 + 1/66) for the drummers,
then (11/78 + 10/77 ... 1/68 + 1/67) and so on. I got around 4.985084.

It appears I don’t understand the English of the question either. I thought the maximum Alex can get for each item is n. So, 12 drummers and a partridge fig. Or 11 pipers and the partridge. Is that correct?

[Anonymous No.12656420]

>>12656327
go to office hours and ask insightful questions. Show that you care about the subject theyre teaching you.

[Anonymous No.12656563]

>>12656196
anyone?

[Anonymous No.12656566]

>>12654698
Or it could be in degrees

[Anonymous No.12656615]

>>12653686
Yes.

[Anonymous No.12657287]

How do I go about integrating a function of this form? I know how to integrate piecewise but this notation is new to me.

[Anonymous No.12657322]

>>12656196
These courses in the pic are trivial if compared to advanced diffeq and computational linear algebra

[Anonymous No.12657329]

>>12657287
Kinda depends on where x0 and x1 are

[Anonymous No.12657396]

how do i get cunny

[Anonymous No.12657405]

>>12657329
They can be anywhere in the domain of the function. Including [eqn]x_1>x_0>x_1+k[/eqn] which is why Im not certain how to proceed.

[Anonymous No.12657565]

>>12657287
Obviously that's
[math]\epsilon (0) = \begin{cases} \epsilon_0 + a_0 \delta (x - x_0) && \text{if} \ x \leq x_1 \\ \epsilon_0 + a_0 \delta (x - x_0) + h && \text{if} \ x_1 < x < x_1 + k \\ \epsilon_0 + a_0 \delta (x - x_0) && \text{if} \ x_1 < x \end{cases} [/math]

[Anonymous No.12657574]

>>12657565
Minor typos.
[math]\epsilon (x) = \begin{cases} \epsilon_0 + a_0 \delta (x - x_0) && \text{if} \ x \leq x_1 \\ \epsilon_0 + a_0 \delta (x - x_0) + h && \text{if} \ x_1 < x < x_1 + k \\ \epsilon_0 + a_0 \delta (x - x_0) && \text{if} \ x_1 + k \leq x \end{cases} [/math]

[Anonymous No.12657611]

>>12657322
So you're saying I should stick with Applied Math in my undergrad because I get to learn advanced DE and computational linear algebra?

[Anonymous No.12657881]

>>12657405
If the integration bounds are [a,b], then the integral of the last term is
h*(max(0,min(b,x1+k)-max(a,x1))
You can check this by analysing the various permutations of {a,x1,x1+k,b} s.t. a<b, x1<x1+k, i.e.
a,x1,x1+k,b => max(a,x1)=x1, min(b,x1+k)=x1+k, Δ=k
x1,a,x1+k,b => max(a,x1)=a, min(b,x1+k)=x1+k, Δ=x1+k-a
x1,x1+k,a,b => max(a,x1)=a, min(b,x1+k)=x1+k, Δ=x1+k-a =>Δ<0
a,x1,b,x1+k => max(a,x1)=x1, min(b,x1+k)=b, Δ=b-x1
x1,a,b,x1+k => max(a,x1)=a, min(b,x1+k)=b, Δ=b-a
a,b,x1,x1+k => max(a,x1)=x1, min(b,x1+k)=b, Δ=b-x1 =>Δ<0

The max(0,...) catches the case where the difference is negative, i.e. if there is no overlap between [a,b] and [x1,x1+k]

[Anonymous No.12657946]

Is Physics 2 (electricity & magnetism) purposely a weed out class? The math is calc 3 and calc 1 was a pre-req. With online it's a clusterfuck and the prof's mic is cutting out every video. This is a certain type of hell

[Anonymous No.12658018]

>>12657946
In my experience, the upper division electricity and magnetism is the filter class for undergrad physics.
Sounds like it's more the professor failing at remote teaching for your case.

[Anonymous No.12658092]

>>12656615
Fuck. Did he say why?

[Anonymous No.12658153]

Just took my first Differential Equations class and I'm a bit worried, will I be okay? I don't really remember much of Calculus 2 and Calculus 3, but I remember the basic stuff like rate of change, basic integrals, basic series, etc, is there some topic I need to get 'good' at? It's probably the first week of semester stress getting to me. I really wish /sci/ had a spoiler feature for text so I can admit that I'm on the verge of crying.

[Anonymous No.12658431]

>>12658153
wtf man its just math. Do the assigned excersices and more if youre worried. Theres nothing particularly difficult about it its mostly just figuring out the forms and applying the rules.

[Anonymous No.12658485]

>>12658153
im also crying about my physics course too much pressure

[Anonymous No.12658499]

>>12658153
You'll be okay, anon. Diff eqs, at least how I was taught it, is just an exercise in identifying what sort of problem you're given, and then recalling the approach to solve that type of problem. It might be good to review some linear algebra, since decomposing some n-order differential system into a system of 1st order linear equations I remember was tricky for me at first, since my memory of eigenvalues and such was rusty. Just sounds like you've got beginning-of-semester stress.

[Anonymous No.12658560]

>>12658018
I'm going to go to a help session. I think I bombed my first lab since it was mandatory hand-in at end of class. I need to understand Gauss' law and electric fields inside spheres.

[Anonymous No.12658571]

>>12657946
>The math is calc 3 and calc 1 was a pre-req.
For mine, you had to take calc 3 at the same time or had taken it before. It also gets worst with stuff like capacitors and inductors.

[Anonymous No.12658701]

>>12657946
Physics 2, Calculus 2, Calculus 3 are imo the biggest filter classes.

[Anonymous No.12658773]

My academic advisor told me that for every credit hour, one should spend three times or four times that amount outside of lecture studying, is this actually true? It sounds insane but a part of me can't help but believe it. He didn't say if this was for an A or for a just passing grade, but it put me in a weird spot. What do you guys think?

[Anonymous No.12658829]

>>12658773
For your major courses, yes. If you're unlucky enough to have to take gen ed, then this doesn't apply obviously.

[Anonymous No.12658833]

>>12658773
Depends on the person & subject matter, different material takes different amounts of time for different people to digest.

[Anonymous No.12658971]

>>12658773
"studying" implies dicking around in the library with undergrad textbooks, which is dumb.
But yes, you should be reading about your specialty and doing research and/or personal projects 24/7

[Anonymous No.12659006]

Is there a package or way to add comments to the align environment in Latex? I have giant blocks of equations and moving in them is such a chore.

[Anonymous No.12659017]

>>12659006
or is there a way to clean this up that I'm missing

[Anonymous No.12659105]

>>12659017
You can always abuse newcommand.

[Anonymous No.12659130]

>>12657322
you there?

[Anonymous No.12659159]

>>12658092
>>/sci/thread/S12592403#p12597883

[Anonymous No.12659293]

>>12659159
I miss the days when Remilia poster and Yukarifag showered /sqt/ with their infinite knowledge...

[Anonymous No.12659413]

>>12659159
Well that was anticlimatic

[Anonymous No.12659490]

>>12659159
>that filename
i thought the 2hu fag used a better filename system, still, if that is him then i wish him the best, i'll still miss him

[Anonymous No.12659583]

>>12656398
Looks like I was way off.

They posted the answer:

This month’s puzzle required a careful computation to remain tractable. One approach that would work: by keeping track of the position of the partridge figurine and the maximum count of identical figurines drawn before it as the twelve different sets of figurines were inserted into the permutation reduced the space into a matrix of size 78 x 12. The final expected value was approximately 6.859787.

[Anonymous No.12659740]

>>12637888
can light bend gravity

[Anonymous No.12660003]

having trouble wrangling this one, I keep getting answers that don't align with the solution. can someone show me how it's done?


i found the roots of the "associated characteristic polynomial" (the characteristic polynomial when it's set to [math]0=f(x) = 10x-13[/math]), but i don't really know how to move forward. the values i kept getting for y(x) and y'(x) are wrong, apparenlty

[Anonymous No.12660094]

>>12660003
samefag, the answer I've got is
[math] y(x) = y_c + y_p [/math]

where [math]C_1 = 1[/math] and [math] C_2 = \frac{2}{3}[/math]

if someone could take a looky-loo and tell me if that's correct, I'd appreciate.

[Anonymous No.12660135]

>>12660094
[math]y'(0) \ne 3[/math] with those constants.

[Anonymous No.12660153]

>>12660135
you're right, i was getting before C_1 = 1 and C_2 = 1 before, and y(0) = 1 and y'(0) = 3 held under those conditions. I just don't get how to pile all this info up into the answer

[Anonymous No.12660211]

>>12660153
[eqn]y(x) = y_c + y_p = c_1e^{2x}\cos{(x)} + c_2e^{2x}\sin{(x)} + 2x - 1 \\
y(0) = c_1 - 1 \\
y(0) = 1 \implies c_1 = 2 \\
\frac{dy}{dx}=e^{2x}(2c_1+c_2)\cos{(x)}-e^{2x}(c_1-2c_2)\sin{(x)} + 2 \\
y'(0) = 2c_1+c_2+2=c_2+6 \\
y'(0) = 3 \implies c_2 = -3[/eqn]

[Anonymous No.12660313]

>>12660211
oof, I was doing [math]y_c(0) = 1[/math]... thanks anon.

so the final answer is simply [math]y(x) = y_c + y_p[/math], with the appropriate substitutions made for C_1 and C_2? And a check to ensure that [math]y'' - 4y' + 5y = 10x-13[/math]?

[Anonymous No.12660320]

>>12660313
To solve a linear ODE you sum the complementary and particular solution, yes.
If you want to check, just use Wolfram Alpha if you don't want to do it manually.

[Anonymous No.12660364]

>>12660003
You're already given the roots of the characteristic polynomial (2±i) in the form of the complementary solution. Just add the particular and complementary solutions then substitute x=0 into the solution and its derivative.
y(x) = y_c + y_p = c1.e^2x.cos(x) + c2.e^2x.sin(x) + 2x-1
y'(x) = 2.c1.e^2x.cos(x) + 2.c2.e^2x.sin(x) - c1.e^2x.sin(x) + c2.e^2x.cos(x) + 2
= (2.c2-c1).e^2x.sin(x) + (2.c1+c2).e^2x.cos(x) + 2

sin(0)=0, cos(0)=1, e^0=1 =>
y(0) = c1-1
y'(0) = 2.c1+c2+2

y(0)=1, y'(0)=3 =>
c1-1=1 => c1=2
2.c1+c2+2 = 3 => 4+c2+2=3 => c2=-3

=> y(x) = 2.e^2x.cos(x) - 3.e^2x.sin(x) + 2x-1

[Anonymous No.12660392]

>>12659740
I know this is a meme but the answer is yes. photons are bosons. That means they can occupy the same quantum state locally. Since each photon has an energy associated with its frequency [math]E=\bar{h}v[/math]. Say you have enough photons concentrated at some arbitrarily small distance from each other with variable frequencies. The since the photon is massless they shouldn't, any this part I'm not sure about, collapse into each other. Then Mr. Einstein tells us that that amount of concentrated energy will bend space time resulting in gravity.

[Anonymous No.12660498]

>>12637888
Could someone tell me where they got 6 from? My understanding is that in a fraction (if this is one), the middle dividing line means that the number on top is the whole, and takes 'superiority' over the bottom number a bit like how we read left to right and each next word in the sentence fills out the picture we are trying to describe more. So 3/2 means that only 2 parts of the 3 whole have been shown? The middle line also represents dividing the two numbers? But I'm guessing they perform 3x2 = 6, so does this mean the middle line can really represent any operation? Sorry if this doesn't make sense I essentially have no meaningful education in mathematics at all.

[Anonymous No.12660511]

>>12660498
Also, since the top number in the fraction/scale factor assumes superiority, does that mean the dilation must be enlargement rather than reduction? Why does 3/2 not = 9 for example, as in, the whole length of the line segment AE is 9, and only 2 of the 3 parts have been represented, thus the whole is 9.

[Anonymous No.12660563]

>>12660498
Just look at the diagram. The length of A'E' = 6 units.

[Anonymous No.12660601]

Is the integral of the inverse of the delta function even possible?

[Anonymous No.12660603]

>>12660601
[eqn]\int\frac{1}{\delta(x-x_0)}dx[/eqn]

[Anonymous No.12661135]

How can black glossy things exist?

[Anonymous No.12661138]

What is this called? I know it’s a pulse, but I can’t find the specific kind.

[Anonymous No.12661236]

>>12661138
Bump

[Anonymous No.12661407]

why does eating white bread always make me feel sick

[Anonymous No.12661487]

>>12661407
wheat or gluten intolerance would be the most likely cause.