/sqt/ /qtddot/ - stupid questions thread

[Anonymous No.16004276]

Previous thread: >>15972871

>what is /sqt/ for?
Questions regarding maths and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>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?
scholar.google.com
>where can I search for proofs?
proofwiki.org
>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
>how do I find the source of an image?
images.google.com
tineye.com
saucenao.com
iqdb.org

>where can I get:
>books?
libgen.rs
annas-archive.org
stitz-zeager.com
openstax.org
activecalculus.org
>articles?
sci-hub.st
>book recs?
sites.google.com/site/scienceandmathguide
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>online courses and lectures?
khanacademy.org
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com
www.chemspider.com

Tips for asking questions here:
>attach an image (animal images are ideal, you can grab them from >>>/an/. Alternatively use anime from safebooru.donmai.us)
>avoid replying to yourself
>ask anonymously
>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 reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

[Anonymous No.16004286]

>>16004276
Why do people worship Landau's book on classical mechanics?
I am reading through it, and it really seems to fail as a textbook.
The book makes insane logical jumps during explanations and just assumes you have already mastered classical mechanics.

[Anonymous No.16004347]

>>16004286
> just assumes you have already mastered classical mechanics.
Which is their appeal (to some). The entire Landau & Lifshitz series is regarded by certain readers as the definitive reference books if you want the rigorous and detailed mathematics on a subject. But yeah, probably not the best books for beginners. They do not so much have a gradual learning curve, instead it's a vertical climb.

[Anonymous No.16004642]

>>16004347
I have the feeling the book assumes a kind of master/apprentice situation, where the master would explain the stuff the book just assumes is true to the apprentice.(eg. a professor giving lectures to students using the book as reference).
But idk, that just means the book is poorly written to me.

[Anonymous No.16004663]

are there any examples of new species evolving in recent times while not being purely speciation

[Anonymous No.16004665]

>>16004642
You might be right. You'll find that many, maybe even the majority, of popular textbooks are based on the author's lecture notes.

[Anonymous No.16004667]

>>16004663
As far as I know this is the best you will get
https://en.m.wikipedia.org/wiki/E._coli_long-term_evolution_experiment
So I don't think we have seen proof of new species.

[Anonymous No.16004670]

Consider a complex function such as [eqn]f(z) = \frac{z}{(z^2+b^2)(z-ia)},[/eqn]where a and b a real numbers.

Is there a quick argument for why this function is meromorphic or do you always have to go through the painstaking process of checking the differentiability using the Cauchy Riemann DEQ.

[Anonymous No.16004779]

I asked ChatGPT to give me a list of anime to watch based on a list of anime I liked and it spit back ....... the same list I gave it.

Why is it so stupid? I don't know enough about computers to know why it's going wrong but I'm curious.

[Anonymous No.16004787]

>>16004670
It's a rational function (the numerator and denominator are polynomials in z). That's all you need.

[Anonymous No.16004789]

>>16004779
Because the AI model at the core of ChatGPT doesn't understand anything. Instead it statistically generates text based upon the input prompt. It's why it typically sucks at math questions. Unless the exact same question and correct answer were part of the data used to build the model it fails badly.

[Anonymous No.16004791]

>>16004779
>Why is it so stupid?
Why are you so stupid?
You should watch what you like, why should it be different?

[Anonymous No.16004822]

[eqn]\int_\mathbb{R} \frac{dx}{x (x-ia)},[/eqn]with [math]a > 0[/math] using the residue theorem. I calculated the residues [math]i/a[/math] and [math]-i/a[/math] at the two distinct poles [math]z = 0[/math] and [math]z = ia[/math]. When closing the integral counterclockwise in the upper half plane I get 0, because both poles are within the contour. However, when I close it in the clockwise direction in the lower half, I get a value unequal to 0, because only the pole at [math]z = 0[/math] is enclosed in the contour.

What's going on here? Why are the two values not equal?

[Anonymous No.16004824]

>>16004822
*Trying to calculate

[Anonymous No.16004827]

I'm stuck. I know I'm supposed to extend the lines and write two more parallel ones, but I cannot find the answers.

[Anonymous No.16004840]

>>16004827
draw parallels to AB through E and F and then extend EB such that it intersects with CD. Then you can use the 30 deg angle and the 120 deg angle in the resulting tetragons to calculate the BEF angle.

[Anonymous No.16004842]

>>16003425
Well, they are British pennies so they are steel with a copper coating.
Are you saying that yes the copper will leech into the water?
And will it be a 'safe' copper, not other harmful things too?

t. complete and utter scence brainlet, but i apparently need copper if im gonna keep taking ascorbic acid. pls halp.

[Anonymous No.16004854]

>>16004840
I cannot, though. I appreciate your help, but I get stuck at finding the rest of the asked angles. It seemed simple as that first.

[Anonymous No.16004855]

>>16004789
So in order to receive a correct answer I must first give it the correct answer? That's limiting.

[Anonymous No.16004856]

>>16004822
The pole at x=0 is on the real axis and apparently you are trying to integrate over the real axis. This is not well-defined. A pole on the contour doesn't count for the residue theorem.

Shift the pole in your integral by some imaginary part epsilon that you will set to zero at the end.
[math] \int_R \frac{dx}{(x\pm i\epsilon)(x-ia)} [/math]
The answer is consistent no matter which half plane you close the contour in (try it), but the answer depends on the sign of +-i epsilon

[Anonymous No.16004875]

>>16004854
I think my initial solution is false. Imagine you extended or shortened the EB line by a few bits. In this case, the angle BEF would change, right? Even though the EBA and CDF and unaltered and AB and CD stay parallel. I think the picture does not provide enough information to calculate BEF.

[Anonymous No.16004880]

>>16004856
thanks, I gonna try that

[Anonymous No.16004895]

>>16004875
It's from my kid's high school. Can you try again, please?

[Anonymous No.16004898]

>>16004855
That class of machine learning algorithm are called Large Language Models. They are great at producing output that seems almost human but only because they are built upon absolutely gigantic databases of text documents. But that's their niche, they are not AGIs. There's no intelligence involved.

[Anonymous No.16004910]

>>16004895
No, because it's not uniquely solvable, so what's the point? Imagine you make the EB line really really short, okay? Does the 30° angle and 120° angles change? No. Do the lines stay parallel? Yes. Is the BEF angle altered. Well, obviously. So you can't calculate an exact solution. Just write this down and say it's something between 0 and 180 deg.

[Anonymous No.16004915]

>>16004827
You don't have enough information in the problem to solve it. You can imagine extending the length of the segment BE while keep the angles ABE and CDF the same. This changes the angles BEF and EFD.

[Anonymous No.16004951]

>>16004856
Okay, I tried it. It's true that the two contour integrals (clockwise and counterclockwise in lower and upper half the plane) are equal. However, the result I get with [math]x + i\epsilon[/math] is different to the result I get with [math]x - i\epsilon[/math]. In the first case I get [math]2\pi/(a + \epsilon)[/math] whereas in the second case I get 0 (obviously, because the contour in the lower half of the plane does not contain singularities). It's wrong for both cases unfortunately, because I should have gotten [math]\pi/2[/math] in case of [math]a = 1[/math].

What am I doing wrong?

[Anonymous No.16004953]

>>16004951
Oh sorry, it's [math]\pi[/math], when [math]a = 1[/math]. I checked with by integrating with a CAS.

[Anonymous No.16004993]

>>16004951
>>16004953
> the result I get with x+iϵ is different to the result I get with x−iϵ
Yes that was my point. Your integral with the pole exactly at x=0 is ill-defined and you get different results depending on how you shift it. But at least it does not matter how you close the contour

You should get 2\pi when you use x+iepsilon. Perhaps you put the pole exactly at x=0 again in your CAS, and it is automatically averaging over both ways of shifting the pole (this is a common way of regularizing the Heaviside function)

[Anonymous No.16004994]

>>16004993
2\pi for a = 1? Yes, I got that after taking the limit as \epsilon approaches 0.

[Anonymous No.16004995]

>>16004994
Yep, sounds like everything's working

[Anonymous No.16005001]

>>16004995
I calculated the integral by hand and eventually arrived at
[eqn]-\frac{i}{a} \ln(-1).[/eqn]
The complex logarithm is ofc ambiguous. However, it gave me an idea. Could a value be assigned to integrals with poles on the contour, if you worked with Riemann surfaces or some sort of equivalence classes? I would cancel out the ambiguity in this case.

[Anonymous No.16005009]

>>16005001
The ambiguity doesn't have to do with the Riemann surface ambiguity. When you calculated it by hand you no doubt used a principal value regularization for the pole at 1/x, saying that the infinite negative part on the negative side of x=0 cancels with the infinite positive part on the positive side. This is a natural regularization but it is a regularization nonetheless. You can prove that the principal value regularization is the average of the two ways of shifting the pole in the limit as epsilon goes to zero.

[Anonymous No.16005014]

>>16005009
You're right, I did that implicitly. I'm gonna use the epsilon argument to reason why it's ill-defined. Thanks.

[Anonymous No.16005019]

Is this correct?
If not, could you guys tell me what did I do wrong? Thank you

[Anonymous No.16005025]

>>16005019
Looks fine to me

[Anonymous No.16005031]

>>16005019
The image includes -1, so you'd use a different bracket ( [ ), right?

[Anonymous No.16005043]

>https://web.archive.org/web/20220702235105/https://www.studyinjapan.go.jp/ja/_mt/2021/06/2020_ga_math_a.pdf
>https://www.studyinjapan.go.jp/en/_mt/2023/07/2019_ga_math_b.pdf

what kind of math do i need to learn in order to pass this 2 exams?

[Anonymous No.16005044]

>>16005031
You are right, I missed that, thanks

[Anonymous No.16005047]

>>16005043
Number theory, geometry, probability, statistics, calculus, and combinatorics should cover everything presented

[Anonymous No.16005762]

Excuse me for the special drawing and general retardation. But does anyone know the formula for calculating the "transform origin"(I don't know what the correct term is) given 2 line segments?

Or does anyone know the correct term so I can google it myself.

[Anonymous No.16005798]

Is there any way to represent a 3x3 identity matrix as a product of vectors?

[Anonymous No.16005852]

You can use the outer product (https://en.wikipedia.org/wiki/Outer_product)), but I don't think you can get around having to add.
[eqn]
I_3 = e_1 \otimes e_1 + e_2 \otimes e_2 + e_3 \otimes e_3 =
\begin{pmatrix}
1 \\ 0 \\ 0
\end{pmatrix}
\begin{pmatrix}
1 & 0 & 0
\end{pmatrix} +

\begin{pmatrix}
0 \\ 1 \\ 0
\end{pmatrix}
\begin{pmatrix}
0 & 1 & 0
\end{pmatrix} +

\begin{pmatrix}
0 \\ 0 \\ 1
\end{pmatrix}
\begin{pmatrix}
0 & 0 & 1
\end{pmatrix}
[/eqn]

[Anonymous No.16005858]

Can somebody give me an intro to measuring signals? Long story short, I want to measure a signal. I am thinking the source of the signal is generating a large field, possibly repeated by satellites. I don't know if it's electromagnetic, microwave, etc. Do I need different equipment to figure this out?

[Anonymous No.16005860]

When I was 11 my IQ was tested at 135. A few years later it was tested at 107. I'm testing it again, should be getting my results next monday.
How do I estimate, based on my previous two results, the outcome for this time?
Btw, is there any logical reason for such a big gap between these two testings? Is IQ supposed to be this much volatile?

[Anonymous No.16005861]

>>16005798
>>16005852
Not as a single outer product because rank(u v^t) would be 1, not 3.

[Anonymous No.16005873]

>>16005860
You can take N(100,15) as Bayesian prior and update twice with your observed measurements to get a new estimated belief about your IQ score.

[Anonymous No.16005913]

>>16005860
> is there any logical reason for such a big gap between these two testings?
Variance but that is quite a large one. Also one of the parameters to generate your score is age. Since 100 is the average for an 11 year old, but if you gave the exact same test answers 10 years later your iq score would be must lower since it would be expected you would have more education and development since then. Your peers will have improved. If you have stagnated it would be reflected in the result.

[Anonymous No.16005927]

>>16005873
>>16005913
Should I expect something lower than, say, 120?
Honestly I'm concerned

[Anonymous No.16005929]

>>16005927
You should be concerned you have fallen for the IQ meme and thinking it actually matters.

[Anonymous No.16005931]

>>16005929
Cope, IQ matters.

[Anonymous No.16005938]

>>16005931
I don't see why the outcome of the test should have any impact on your life.

[Anonymous No.16005940]

>>16005938
There are psychological, ideological and sociological reasons for me to care about IQ.

[Anonymous No.16005946]

>>16005931
>>16005940
By your lack of critical thinking I strongly suspect 107 was the correct score for you.

[Anonymous No.16005956]

>>16005946
Saying that IQ does not matter having low/average IQ, would be coping.
Saying that IQ does not matter having high IQ would be critical thinking.
Either way, we have low IQ [math]\iff[/math] dumb and high IQ [math]\iff[/math] smart.
If I really have low IQ, I'd rather be labeled as an idiot than a coping idiot.

[Anonymous No.16005968]

>>16005956
There are quicker ways of telling everyone you've never had sex.

[Anonymous No.16005982]

>>16005762
Looks like a fixed point.

[Anonymous No.16006028]

>>16005762
>>16005982
I ended up getting the distance each point in the line travelled, then applied distance ratios to the first line and it magically works.

[Anonymous No.16006040]

>>16005968
why do women when they get mad always start thinking about having sex with me?

[Anonymous No.16006041]

>>16005762
for this particular operation (dilation) I would call it:
>the center of dilation

[Anonymous No.16006067]

what do?

[Anonymous No.16006077]

>>16006067
weird fucking question, even x^2 has two possible values

[Anonymous No.16006084]

>>16006077
the answer is -4 it seems

[Anonymous No.16006091]

>>16006067
>>16006084
Why would it be -4?

[Anonymous No.16006093]

>>16006091
Idk, perhaps there's some mistake with the answer or the question itself

[Anonymous No.16006101]

>>16006093
I can get the answer -4 but only if the question is written incorrectly and is actually:

If [math]4x^4 = 7x^2 + 1[/math], then what is [math]2x^2 - \sqrt{3}x - 5[/math].

[Anonymous No.16006106]

>>16006041
Ah "center of dilation", thanks

[Anonymous No.16006122]

>>16006084
It's a typo. [math]\sqrt{3x}[/math] should be [math]\sqrt{3}\ x[/math].

[Anonymous No.16006125]

>>16006122
Ok
>>16006101
U first found the value of x2 and then x and just substituted it?

[Anonymous No.16006129]

>>16006125
[math]4x^2 + 1 = 7x^2 \\
(2x^2 - 1)^2 + 4x^2 = 7x^2 \\
2x^2 - 1 = \sqrt{3}\ x[/math]

Then substitute into the second equation.

[Anonymous No.16006132]

>>16006125
[math]4x^4 + 1 = 7x^2 \\
(2x^2 - 1)^2 + 4x^2 = 7x^2 \\
2x^2 - 1 = \sqrt{3}\ x[/math]

Then substitute the rhs term.

[Anonymous No.16006135]

>>16006132
Thx

[Anonymous No.16006166]

How would you find the voltage between A and B here? What I'm looking for here is Thevanine's voltage btw.

[Anonymous No.16006176]

>>16006132
henlo anon, how did u type the equations? Is it latex or mathjax? Plz share the resource for learning it.

[Anonymous No.16006180]

>>16006176
latex but you have to use [math] tags on this board.

[Anonymous No.16006197]

>>16006180
ok

[Anonymous No.16006218]

>>16004276
Go make protendo better

[Anonymous No.16006253]

>>16006166
https://en.m.wikipedia.org/wiki/Nodal_analysis

[Anonymous No.16006324]

Pic related is from Axler's LADW. Is it correct?
My reasoning is that:
> (V -> W) (W -> V) = (V -> V)
> (W -> V) (V -> W) = (W -> W)
So [math]TT^{-1} = I_V[/math] and [math]T^{-1}T = I_W[/math], which is the opposite of what he says.

[Anonymous No.16006339]

>>16006324
The book is correct,

[Anonymous No.16006340]

>>16006324
ST operator means apply T then apply S.
T operates on V and S results in V.
Therefore ST is V->V identity.
Analogous for TS.

[Anonymous No.16006345]

>>16006340
Okay, thank you.

[Anonymous No.16006453]

''The white fathers told us: I think, therefore I am. The black mother within each of us—the poet—whispers in our dreams: I feel, therefore I can be free'

can you refute black philosopher Audre Lorde 's argument?

[Anonymous No.16006499]

>The average mass of the eighteen blood samples was 0.0489g and that of the distilled water controls was 0.0492g
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4590883/

If blood is water plus various other things, how can its mass be lower than water? This also implies that the density of blood is lower than that of water. I don't understand.

[Anonymous No.16006562]

>>16006499
Scroll down. The deviation in the blood measurements was vastly greater than that of the water controls.

[Anonymous No.16006745]

Why was this shut down?
https://en.wikipedia.org/wiki/Mirror_Fusion_Test_Facility

[Anonymous No.16006826]

Here's a retarded question.
I'm asked to find the domain of the function f(x) = (x^2-1)/(x+1)
If I input -1 into the function I get 0/0 which is undefined.
But the function can be rewritten as f(x) = x - 1, if I multiply the denominator and numerator with (x-1) which makes -1 an acceptable input.
What gives? Is -1 part of the domain or not?

[Anonymous No.16006840]

>>16006826
It's what we call a "removable discontinuity", or a hole in the graph. It's not part of the domain. However, as you've noted, you can find a function that is identical at every point but DOES have it in the domain. Because of that, they can easily be treated as the same function for almost all intents and purposes, but formally speaking they are not equivalent.

[Anonymous No.16006856]

>>16006840
>removable discontinuity
Thanks man for giving me a term.
I'm self studying as a hobby so I don't have a teacher to ask.

[Anonymous No.16006865]

>>16006840
>>16006856
Well, I suppose if we're being completely strict, the proper term here is actually "removable singularity", because a removable discontinuity is only for cases where the "jump" is still within the domain.
But you'll see a lot of people use discontinuity for both

[Anonymous No.16007028]

>>16006826
>find the domain of the function
The domain can be whatever you want.
The correct way to specify a function should is to also supply the domain.
For example f(x) = x+1, for x positive real->reals is a different function than g(x) = x+1, for x even natural->naturals.
The correct question in your case is what real values cannot be in the domain.
Or what is the largest subset of reals that could be a domain for the given expression.

[Anonymous No.16007034]

>electronics lab
>have to get the IV curve of the forward and reverse bias of a diode
>nobody except me can get the reverse bias
>professor is stumped too
I have to have done something wrong, but my measurements line up with the spec sheet of the diode well

[Anonymous No.16007136]

Is there an example of a non-ionic solute a solution of which has a greater conductivity than the solvent alone?

[Anonymous No.16007143]

I know mentally that N=3 but how do I get to it on paper?
I cant solve 4+n; what do I do to get a 3?

[Anonymous No.16007153]

>>16007143
The bigger challenge is trying to read that handwriting. That's horrific and barely legible. I honestly have no idea what the question is meant to be.

[Anonymous No.16007170]

>>16007153
I need to find the value of a and n.
But when I do the math I get to a point where I get 4+n (exponents)
I know that n is 3 because 7-4=3
But how do I solve 4+n?

[Anonymous No.16007183]

>>16007170
[math]x^7=(x^4)(x^3)[/math]
[math]x^{4+n}=(x^4)(x^n)[/math]
so just divide both sides by [math]x^4[/math]

[Anonymous No.16007187]

this isnt a question so much as a statement but it kinda sucks that I got out of my undergrad without really ever getting to delve super deep into mathematics or physics

now if i want to get back into it i either have to try and study through reading books alone by myself like a schizoid or pay a lot of money to go back to school for a degree that probably will not increase my salary in a way that justifies it

has anybody here gone back to school for math or physics and found it a good idea

[Anonymous No.16007192]

>>16007170
That's meant to be a 4? Seriously?

[Anonymous No.16007196]

>>16007183
You are horrible at explaining.
Could you try again please?
Or someone else? What is the next step?

[Anonymous No.16007199]

>>16007196
You solve 4+n=7 by subtracting 4 from both sides to get the 7-4=3 that you know.
You do this by dividing by x^4.

[Anonymous No.16007202]

>>16007187
Depends on what you mean by a 'good idea'. Ask yourself why would you want to do that. Money, a new career, intellectual curiosity, boredom?

[Anonymous No.16007203]

>>16007192
Yeah, its a 4. What should I do now that I got 4+n??

[Anonymous No.16007211]

>>16007203
What do you mean how? Do you even know how to handle exponents??

[Anonymous No.16007212]

>>16007199
>>16007211
I kinda understand what you want me to do but I dont know how to do it

[Anonymous No.16007215]

>>16007202
>Money, a new career, intellectual curiosity

A mixture of these three

I work as a software engineer right now but it seems like a lot of the more interesting work is gatekept behind academic requirements (oftentimes a phd, less often a master's)

I guess what I'm looking for is a way to dip my toes in to see if it's something I really like before I go whole hog into a program

[Anonymous No.16007218]

>>16007212
wtf is that colon : meant to mean? that's some weird notation.

[Anonymous No.16007222]

>>16007218
It's an uncommon notation for division, but by no means an unheard of one (and it's the standard in some places in Europe, like using . in place of , when writing out e.g. 1,000,000)

[Anonymous No.16007226]

>>16007215
>I work as a software engineer
I've worked in that sector and I've seen several paths other people have taken. Night classes, online courses, part-time degrees (often sponsored by their company). What I haven't ever seen is people dropping out to go back to school. Once you have an income it's hard to lose that especially if you have living expenses.

[Anonymous No.16007227]

>>16007218
>>16007192
>>16007183
Kys all, niggers, thanks for the help

[Anonymous No.16007233]

>>16007212
Do you know how to simplify these: [math]x^ax^b = ?,\ x^a / x^b = ?[/math]

If not you back to your textbooks and learn the basics again.

[Anonymous No.16007234]

>>16007226
>part-time degrees (often sponsored by their company)

this is something i hadn't considered before, definitely worth looking into

[Anonymous No.16007243]

>>16007234
It's quite common because it almost guarantees that staff member will likely remain with the company during the degree. Also there are often tax benefits for them providing training.

[Anonymous No.16007248]

>>16007233
Fuck a textbook, nigger. You dont know how to teach

[Anonymous No.16007249]

>>16007248
You can't teach stupid.

[Anonymous No.16007250]

Let [math]\mathbb{k}, \ell[/math] be fields with [math]\mathbb{k} \subset \ell[/math]. Recall that [math]\ell[/math] is a [math]\mathbb{k}[/math]-vector space, and assume [math]\operatorname{dim}_{\mathbb{k}} \ell=d<\infty[/math].
a) Let [math]V[/math] be a [math]\ell[/math]-vector space of dimension [math]r[/math]. Prove that [math]V[/math] is also a [math]\mathbb{k}[/math]-vector space and calculate its dimension over [math]\mathbb{k}[/math].
b) Now, let [math]W[/math] be a [math]\mathbb{k}[/math]-vector space of dimension [math]s[/math]. Prove that [math]V=\operatorname{hom}_{\mathbb{k}}(\ell, W)[/math] is a [math]\ell[/math]-vector space and calculate its dimension.

I'm struggling with the last part of point b. I can calculate the dimension as a [math]\mathbb{k}[/math] vector space, but I'm not really sure how to do it over [math]\ell[/math], any ideas?

[Anonymous No.16007287]

>>16007250
easiest thing is to try examples. finite fields would work but [math]\mathbb {R,C}[/math] would be convenient

[Anonymous No.16007288]

>>16007287
But that wouldn't be a proof, it's an exam question I must be formal.

[Anonymous No.16007291]

>>16005047
thank you

[Anonymous No.16007305]

>>16007250
>Prove it’s an l-vector space
The question is a bit funny, because you need to define scalar multiplication yourself, probably as taking place before the homomorphism. Anyway you want some kind of division right? Well the usual way to do that is to see when you go from “over k” to “over l”, certain pairs of vectors that were independent, now become dependent… so your previous basis separates into equivalence classes, hopefully all of the same size…

[Anonymous No.16007310]

>>16007249
Retard, I know that the when you divide, you rest the exponents. What I want to know is what to do when I get to the 4+n

[Anonymous No.16007322]

>>16007310
Cigan
You take this >>16007212
write x^(4+n) as (x^4)*(x^n), then divide both side with x^4, leaving you with x^n on one side, which even a cigan like you can solve for general 'x='

[Anonymous No.16007343]

>>16007322
Write it down for me

[Anonymous No.16007350]

>>16007322
I mean, I get it, but I dont know exactly how to do it
I know pic related is wrong but close

[Anonymous No.16007353]

>>16007322
>>16007350
Just get a piece of paper and do it for me so I can see, please, help a fren out

[Anonymous No.16007356]

>>16007350
YOU DUMB NIGGER, GORILLA CIGAN
-(5/6) multiplies x^(4+n), that means it multiplies both x^4 AND x^n, it's just a different way of writing the original x with exponents
You divided x^4 with x^4, how can there still be an x. It's x^0 which equals 1.
You already did it right on the left side, why are you shitting up the right side.

a*x^2 = -(5/6)x^n

[Anonymous No.16007459]

>>16007356
Thank you, this is makes me feel retarded when I finally solve it

[Anonymous No.16007545]

>>16007305
>you need to define scalar multiplication yourself
shouldn't the action be unequivocally defined?

[Anonymous No.16007663]

>>16007545
well no, consider the example C -> C over R, the action of z could be to multiply by z but could also be to muktiply by its conjugate it wouldnt change the dimension of course its just unusual to leave these possibilitys dangling

[Anonymous No.16007698]

Pls determine this quickly for me and show how:
[eqn]\int \sqrt{1 + \frac{1}{x^2}} \,dx[/eqn]

[Anonymous No.16007712]

>>16007698
There's nothing quick about solving that.

[Anonymous No.16007724]

"Since 2^n > n when n > 2", shouldn't it be when n > or = 0? Or at least n > 0 since 1/2^n < 1/n? Am I a retard or is Peter Lax the retard?

[Anonymous No.16007913]

>>16007663
But then, they are different vector spaces, so for a vector space it's unequivocally defined.
Let [math]k \subset l[/math] be a field extension.

Proposition: If [math]V[/math] is an [math]l[/math]-vector space, then [math]V[/math] is a [math]k[/math]-vector space and [math]\operatorname{dim}_k V=\operatorname{dim}_l V \operatorname{dim}_k l[/math].
Proof: Define the scalar multiplication [math]k \times V \rightarrow V[/math] to be the restriction of the given scalar multiplication [math]l \times V \rightarrow V[/math]. This makes [math]V[/math] a [math]k[/math]-vector space. Next, it is easy to check that if [math]\left\{x_1, \ldots, x_d\right\}[/math] is a [math]k[/math]-basis for [math]l[/math] and [math]\left\{y_1, \ldots, y_n\right\}[/math] is an [math]l[/math]-basis for [math]V[/math], then [math]\left\{x_i y_j: 1 \leq i \leq d, 1 \leq j \leq n\right\}[/math] is a [math]k[/math]-basis for [math]V[/math]; hence,
[math]
\operatorname{dim}_k V=n d=\operatorname{dim}_l V \operatorname{dim}_k l .
[/math]
Corollary: If [math]V[/math] is an [math]l[/math]-vector space, then [math]\operatorname{dim}_k l[/math] divides [math]\operatorname{dim}_k V[/math] and [math]\operatorname{dim}_l V=\frac{\operatorname{dim}_k V}{\operatorname{dim}_k l}[/math].

Thus, for [math]V=\operatorname{Hom}_k(l, W)[/math], if you prove that the scalar multiplication [math]l \times V \rightarrow V[/math] that you found is the extension of the usual scalar multiplication [math]k \times V \rightarrow V[/math], then by this corollary we have that
[math]
\operatorname{dim}_l V=\frac{\operatorname{dim}_k V}{\operatorname{dim}_k l}
[/math]


The equality
[math]
\operatorname{dim}_l V=\frac{\operatorname{dim}_k V}{\operatorname{dim}_k l}
[/math]
can only be true if the action on [math]V[/math] is unequivocally defined (which it's, otherwise it would be a different vector space).

Am I missing something?

[Anonymous No.16007967]

How do I get a better memory? I had my IQ tested at the weekend and I have a memory worse than 99.6% of the population. I lose my train of thought very easily and often forget what I'm talking about midsentence. I use to think I was absent minded but now I have hard proof that even when I'm trying to can't remember anything. My mom use to recite phone numbers to me when I was younger and hit me if I couldn't recite them, but that clearly didn't work.

[Anonymous No.16008047]

In your experience how much of an exam you need to know to get a passing grade? Other anons in Uni (more specifically European Unis), how much % of the exam was a C grade in your first semester?

[Anonymous No.16008101]

>>16008047
There is no single answer to that. It could be a fixed point system or scaling marks and is totally course, lecturer or even university dependant.

[Anonymous No.16008141]

>>16004276
How is tungsten denser than lead if lead has a higher atomic number while they're both metals?

[Anonymous No.16008147]

>>16008141
While an atom of lead is heavier than an atom of tungsten, the latter is significantly smaller than the former. More than enough to offset the actual mass difference.

[Anonymous No.16008150]

I want to learn computational neuroscience. Can someone recommend the top textbook in the field?

[Anonymous No.16008151]

>>16008147
oh because tungsten has less electron shells or energy levels
that makes sense

[Anonymous No.16008168]

Can someone tell me how to reach that solution?
I get X3-216.
Where the hell did -18X2 and +108X come from? Whats the formula/correct way to solve this?

[Anonymous No.16008173]

>>16008168
You've fallen for the freshman's dream. [math](x+y)^n \neq x^n + y^n[/math] in general. Multiply things out and distribute them.
[math](x-6)^3=(x-6)(x-6)(x-6)[/math]
[math](x-6)(x-6) = x(x-6)-6(x-6) = x^2-6x-6x+36 = x^2-12x+36[/math]
[math](x-6)(x^2-12x+36) = x(x^2-12x+36)-6(x^2-12x+36) = x^3 - 12x^2 + 36x - 6x^2 + 72x - 216 = x^3-18x^2+108x-216[/math]

[Anonymous No.16008199]

>>16008173
Thank you!

[Anonymous No.16008428]

>>16008168
> I get X3-216.
This is painful to look at. It reminds me of myself doing math, when I was 10.

[Anonymous No.16008619]

How to solve this?

[Anonymous No.16008621]

And this. What is the formula/way to solve it?

[Anonymous No.16008625]

>>16008619
>>16008621
> If you want help with your homework, go to /wsr/ - Worksafe Requests

[Anonymous No.16008634]

>>16008619
>p(x) has -2 as one of its roots
hint This is the same as saying that p(-2)=0.

[Anonymous No.16008635]

>>16004276
My colleague was telling me that chatgpt 4 with math add on was good for math and hasn't been wrong for any of his calculus word problems yet. I think he said mathai and math solver.
Is this ai actually still terrible for math? And if not, is gpt 4 easily piratable?
If not, are there comparable free/cheaper alternatives(pref not subscription based) for math?

[Anonymous No.16008659]

>>16008634
Thanks, that's all I needed. The book I'm working with takes for granted that I already know a lot of shit that I dont and is very vague with descriptions.
>>16008625
Die slowly

[Anonymous No.16008718]

>>16008634
What am I doing wrong? I get 16/5 but the book says the result is 8/7

[Anonymous No.16008734]

>>16008718
When you expand 3(k-2) to 3k-6, you have to remember that you're still supposed to be multiplying the entire thing by that 4.
Not just the -6.

[Anonymous No.16008752]

>>16008734
Thanks!! Now I got 8/7

[Anonymous No.16008753]

>>16008659
>>16008718
If you need this kindergarten level of math explained to you, you have clearly missed out on several years of school.

[Anonymous No.16008765]

>>16008753
Yeah I fucking know, I was dying inside on school, being a fucking loser, I didnt learn shit. Then I left and spent years fucking around trying to fix my life. Now I'm trying to get into a college in my mid 20s and I need to pass a math exam.
I know this stuff is easy af but I have no money to pay somebody to teach me and I barely remember anything.
Just help me when you can, it's not like it cost you anything and you supposedly like math so wth

[Anonymous No.16008769]

>>16008765
That's not the point. The point is you have skipped over some basic knowledge on your re-education. You are trying to run before you can walk. If you keep failing on basic, simple shit how are you expecting to go any further?

[Anonymous No.16008771]

>>16008769
Sometimes I forget, somethings I still have to learn but I learn fast.
I literally started from 0 a month ago. I remember/knew close to nothing.
Dont worry about me, mind your own and answer when you can and if you cant, dont.
Dont make come looking for you

[Anonymous No.16008772]

>>16008771
Whatever, fuck my english, kys
Answer if you want, if you dont, dont. Dont worry about me, I'm gonna make it

[Anonymous No.16008807]

>>16008765
You gotta go through khanacademy and watch and study what you don't know. If you have questions you can ask.

[Anonymous No.16008873]

>>16008769
bro yeah it was a mistake to forget the ( ) pair, but catching mistakes is the whole point of doing practice problems. cool your tits
>khan academy
good idea, but not the only possible approach. practice problems are fine for many people

[Anonymous No.16008877]

How am I supposed to find the R value for 1500? Here are the values that are given to me.
1000=0
1200=.0365
1400=0.0675
1600=0.0944
1800=0.1181
I don't have access to the formula for the function, and this is an early calculus class.

[Anonymous No.16008975]

I have the recurrence F(x)=2F(x/2)+x/log(x)

How do i prove using induction that: F(x) is big-O of log(log(x))?

I need to show F(x) <= c[x*log(log(x))] but I don't know how to prove
c[x*log(log(x/2))] + x/log(x)
is less than
c[x*log(log(x))]

Any help would be appreciated

[Anonymous No.16009188]

>>16008873
You're the anon who has been posting in multiple threads with questions too stupid even for /sqt/. You have repeatedly demonstrated a total lack of fundamental education and even when given the answers you don't understand them. Your grasp of elemental math has more holes than pornhub. Take the advice, take a few steps back and start with Kahn Academy from the beginning.

[Anonymous No.16009295]

>>16008975
It is certainly not O(log(log(x))) because it grows at least linearly because of the 2F(x/2) part.
Expanding twice you see that [math]F(x)=2^2F(x/2^2)+\frac{x}{\log x - \log 2} + \frac{x}{\log x}[/math] and so also (induction) [math]F(2^n)=2^nF(1)+\sum_{i=0}^{n-1}\frac{2^n}{n - i}=2^nF(1)+(1+o(1))2^n\log n[/math] where I pretend [math]\log(2)=1[/math] because the base doesn't matter for asymptotics.
Then (this is not at all clear from the above and you have to look at numbers in between powers of two, or at least bound them) [math]F(n)=nF(1)+(1+o(1))n\log\log n=O(n\log\log n)[/math], which I think is what you want.

>Please wait a while before making a post
Bots don't mind waiting but I do...

[Anonymous No.16009327]

How would a massive volcanic activity look like?
I know that geology operates on different timescales, but I was recently reading about trap formations and I have hard time imagining how, for instance, Deccan or Siberian traps formed over 2 million years.

[Anonymous No.16009348]

chemistry and foodsci anons, i want to test the fat content and profile of the cooking fat I buy.
is it possible or practical to differentiate out the approximate the SFA, MUFA, and PUFA ratios?
Otherwise how would I find a lab to good test a supplied sample for them with perhaps a breakdown by fatty acid in the UK?

What made me think about was coming across a reference to this article talking about modern pig fat being high in PUFA and while I had been under the impression that animal fats were generally highest in palmitic, stearic, and oleic acids, it said some tests found PUFA at 32%

https://web.archive.org/web/20130206131742/https://www.westonaprice.org/blogs/cmasterjohn/2011/11/25/good-lard-bad-lard-what-do-you-get-when-you-cross-a-pig-and-a-coconut/#gsc.tab=0

A secondary concern I have is from adulteration with cheap seed oils.
I'm a little concerned about the effects of high linoleic acid in the diet on health and was trying to reduce my degree of exposure but this opens up a minefield.

I appreciate any advice you might offer.

[Anonymous No.16009441]

>>16009327
Pretty sure flood basalts aren't eruptions but instead continuous lava outflowings. Such events happen today but what sets traps apart was the shear amount of magma involved.

[Anonymous No.16009504]

>>16009188
>Stop posting stupid questions in the stupid questions thread!
...

[Anonymous No.16009700]

How do I find K? What is the first step/formula?

[Anonymous No.16009751]

>>16009295
ty anon, do you know how i can prove using algebra that
c[x*log(log(x/2))] + x/log(x) is less than c[x*log(log(x))]?

it is one of the requirements of induction to exactly derive the inductive hypothesis

i have F(x) <= c[x*log(log(x/2))] + x/log(x)
and i need to do some more steps to get from there to
F(x) <= c[x*log(log(x))

i know for sure that c[x*log(log(x/2))] + x/log(x) is very slightly less than c[x*log(log(x)) asymptotically, but i dont know how to make this happen using algebra or anything else

[Anonymous No.16009755]

>>16009700
Solve for y, substitute y for that

[Anonymous No.16009761]

>>16009700
If only the question told you what the values for x & y should be ...

[Anonymous No.16009775]

>>16009441
That still classifies as volcanic activity IIRC. By the way, what's the reason behind the shape of these (and many other) trap rocks?

[Anonymous No.16009797]

>>16009755
>>16009761
Nice, thanks.
What about this one? Is X=3? Or Y?

[Anonymous No.16009806]

>>16009797
jesus wept, go google what the slope of a line means. you really are a retard aren't you.

[Anonymous No.16009815]

>>16009806
I know what it is, but I dont know what to do when they ask me to find k.
Just tell me how to find K

[Anonymous No.16009820]

>>16009815
if you knew and understood what it means you wouldn't be asking the question.

[Anonymous No.16009832]

>>16009820
Okey thank you.

[Anonymous No.16009841]

>>16009797
Somebody please?

[Anonymous No.16009850]

>>16009841
Ask yourself what is the equation for a line and how do you calculate its slope?

[Anonymous No.16009866]

>>16009850
y2-y1/x2-x1?
Just tell me dude, I'm learning so much at the same time and I only got a few weeks left

[Anonymous No.16009870]

>>16009866
That is the equation for the slope, not the equation for a line. Why are you trying to answer this kind of question if you don't even know that?

[Anonymous No.16009901]

>>16009751
Well, if [math]x[/math] is large enough then [math]\frac{x}{\log x} \leq x \leq x\log \log x[/math] while also [math]x\log\log(x/2)\leq x \log \log x[/math].
This is because as [math]x\to \infty[/math], [math]\log x \to \infty[/math] and [math]\log\log x \to \infty[/math], and so at some point these are at least 1.
You say you already know this is true?

[Anonymous No.16009917]

>>16009870
What is the equation of a line?

[Anonymous No.16009951]

>>16009797
Can somebody tell me how the fuck to find K? Thanks

[Anonymous No.16009956]

>>16007698
>(a) trig substitution with x = tan(\theta) and dx = sec^2(\theta) d\theta
>(b) addition identity
>(c) definition of tan and sec
>(d) trig Pythagorean theorem
>(e) antiderivative of csc is in your table
>(g) derivative of sec is in your table, too

[Anonymous No.16009974]

>>16009917
> please spoonfeed me the answer so that I don't learn anything.
> I don't know how to use a search engine.

[Anonymous No.16009980]

>>16009917
f(x) = ax + b

[Anonymous No.16009999]

>>16009797
bro, this is trivial stuff. the form of the question is a massive clue.

general equation for a line: ax + by + c = 0
slope = - a / b

[Anonymous No.16010002]

>>16009797
bro, this is trivial stuff. the form of the question is a massive clue.

general equation for a line: ax + by + c = 0
slope = - a / b

[Anonymous No.16010038]

>>16004276
Should I add in-text citations in a power-point presentation? In this case, it would look very ugly as I have to add "[n]" at the end of each bullet point. Is it enough if I list all the references at the end of the presentation? But this time the reader doesn't know which reference belongs to which text.

[Anonymous No.16010062]

>>16009980
>>16010002
How do I find K?
Answer the question please

[Anonymous No.16010068]

>>16010062
ngmi

[Anonymous No.16010081]

>>16010062
> Is it enough if I list all the references at the end of the presentation?
Yes. It's a presentation. No one will check references during a talk.

>>16010062
You have *zero* common sense. Just apply >>16010002 to >>16009797. If you're trying to cram for an exam I can tell you now, good luck, you need it.

[Anonymous No.16010114]

>>16009901
thank you anon

i plotted y = x[log(log(x))] - x[log(log(x/2)) + 1/logx] on a graph and when x = about 5 it starts to tend upwards to infinity

i just was hoping i could use some math magic to show this is true, rather than having to say something like "by plotting on a graph this holds for x >6".

[Anonymous No.16010228]

I made a silly script that converts the normal latex notation to the one used in /sci/ (the one with [math]), do someone find this useful? If you want to I could share the script or my site.

[Anonymous No.16010233]

Vaguely TF2-related question: can a PhD thesis cover multiple subjects at once and therefore count for multiple degrees?

[Anonymous No.16010244]

>>16010081
Where do I put the 3? On x or y?
Slope: -a/b doesnt really tell me much, I'm learning still, I'm a student

[Anonymous No.16010250]

>>16010244
> [math]4x - ky - 7 = 0[/math]
> [math]ax + by + c = 0[/math]
Are you seriously asking what a & b are?

[Anonymous No.16010252]

>>16010081
Something like this?
I know how to solve it when its just the x and the y there but the K fucked me up
Pls help

[Anonymous No.16010260]

>>16010252
Completely wrong. I don't want to give you the answer because it's obvious it isn't going to help because you have no idea at all what you're doing and seem incapable of understanding basic math. Everything you need is here >>16010002 and here >>16010250. A child could solve this.

[Anonymous No.16010322]

>>16010260
-4/k =3?

[Anonymous No.16010333]

>>16010322
Yay! You finally got it ... though you have the sign wrong: [math]3 = - a / b = - (4) / (-k) = 4/k[/math].

[Anonymous No.16010369]

Pondering exercise 2.8 in Miessler. Why couldn't [math]r[/math] and [math]s[/math] just be both integers instead of equivalent? all that seems to matter is that they're both integers and that [math]\cos sa[/math] is equal to some multiple of 2π. Just give me a hint, I haven't given up all hope. Is the solution in the derivative on the other side of the simplified wave equation?

[Anonymous No.16010374]

>>16010369
If you want an answer then post the question you retard. Why do you expect anyone here has that book or cares to look it up??

[Anonymous No.16010385]

>>16010374
>>16010369
At this point, I assume that the answer only makes sense when taking the five principles listed above into account, so sorry for the long image.

[Anonymous No.16010391]

>>16010385
The problem is to prove the [math]r = s[/math] equation at the bottom of the image.

[Anonymous No.16010399]

>>16010385
> Why couldn't r and s just be both integers
Because you start with a general solution which has no such restriction. It is only when you impose the boundary conditions that the energy will be quantized and hence will be reflected in r and s.

[Anonymous No.16010467]

>>16010333
K=12?

[Anonymous No.16010471]

>>16010467

[Anonymous No.16010479]

>>16010471
-12=k?

[Anonymous No.16010506]

>>16010471
K=20?

[Anonymous No.16010661]

What do I set c to be if I want the maximum of the following function to be at a particular input value v? [eqn] B\left(v\right)\ =\ \frac{v^{3}}{e^{\frac{v}{c}}-1} [/eqn]

I guess I could do gradient descent but I feel like there is an equation I could use. I got v×lambertw(3×exp(3))+3 after fiddling around with sympy but it's not quite right.

[Anonymous No.16010687]

>>16010661
Oh, I feel so stupid. It's just linear.
c = 2.82143937v
I wonder what the constant is.

[Anonymous No.16010703]

>>16010661
I googelde 2.82 and it said something something Planck spectrum blackbody

[Anonymous No.16010707]

>>16009775
I want to fugg Basalt-chan

[Anonymous No.16010725]

>>16010703
That's what it is. "Something something Planck spectrum blackbody constant" is just about the most helpful thing you could call it, except this has to do with phonons instead of blackbody radiation.

[Anonymous No.16011098]

>>16010661
Algebraically, it seems straightforward to solve for c.
Just cross multiply, add 1, natural log both sides, and
multiply by 1/v. A final reciprocal of both sides gives the
equation:
[eqn] c= {v \over \ln \left({v^3 \over B(v)}+1 \right)} [/eqn]

[Anonymous No.16011190]

>>16009797
Whats the value of K? Anyone?

[Anonymous No.16011191]

>friend says universe can't possibly be infinite
>tell him he is stupid of course it's possible we just don't know
>he says it can't be because we would never have reached today if there was an infinite amount of days before today
>tell him he is stupid again and leave
Um...is he right or wrong though? It doesn't feel right but it sounds right

[Anonymous No.16011198]

>>16010506
>>16010479
>>16010467
>>16010002
>>16009980
>>16009797
Can somebody tell me how to find K step by step please? Explain like I'm 5

[Anonymous No.16011218]

>>16011190
>>16011198
Serious question, are you fucking retarded? A 5 year old wouldn't be this stupid. You had the answer here >>16010333

[math]3 = 4/k \implies 3k = 4 \implies k = 4/3[/math].

[Anonymous No.16011248]

>>16011218
Could the solution also be k=3/4?

[Anonymous No.16011250]

>>16011248
I mean 4.3=k?

[Anonymous No.16011262]

>>16011250
No. That's simply impossible. Are you honestly trying to do math and don't even know the basic rules of algebra? That's like trying to read a book when you don't know the alphabet.

[Anonymous No.16011266]

ban the brainlets

[Anonymous No.16011334]

is there a way to prove that:
[math]\frac{x}{lnx} - log(log(x)) > 0[/math]
for an arbitrarily large x?

[Anonymous No.16011349]

Why does my prof hype up the tensor product like it's the second coming? I'm a physics person, what do I get out of it, scientifically speaking?

[Anonymous No.16011353]

What is the best suicide method given that I don't have access to guns and drugs?

[Anonymous No.16011372]

>>16011334
Why have you mixed ln and log? Mistake or intentional?

[Anonymous No.16011379]

>>16011262
And where do I find these so called "rules of algebra"?

[Anonymous No.16011380]

>>16011379

[Anonymous No.16011388]

>>16011218
K=-3? Or 3?

[Anonymous No.16011389]

>>16011379
> Please Use Google For Me Coz I'm An Idiot
https://faculty.ung.edu/mgoodroe/PriorCourses/Math_0999_General/The%20Formal%20Rules%20of%20Algebra.pdf

[Anonymous No.16011394]

>>16011389
Not clicking that.
Youtube tells me m=-a/b so that leaves me with -(-4)/-k = 4/-k, no? That would mean the result is -3 or 3?
Because >>16010333 confused me with th signs

[Anonymous No.16011396]

>>16011353
Dumb nigger, you can't even kill yourself properly.
It's jumping off the highest building you can find, you won't be able to undo that.

[Barkon No.16011398]

>>16011396
Undo this.

Faggot.

[Anonymous No.16011400]

>>16011394
> Not clicking that.
wtf?! But sure, you do you. Having a cheat sheet with all the rules would be no help to you at all ...

> Youtube tells me m=-a/b
That works too.

> so that leaves me with -(-4)/-k = 4/-k, no?
No it doesn't. a = 4, b = -k so -4/-k = 4/k

> That would mean the result is -3 or 3?
Huh? What twisted brain logic makes you think that? It's utterly wrong.

[Anonymous No.16011407]

>>16011400
>-4/-k = 4/k
But why does the - dissapear? I know that -.-=+ but you didnt touch anything yet so why changed the symbol already?
I mean... -2.-4=8. But you are telling me I can do -2.-4= 2.4=8???

[Anonymous No.16011411]

>>16011407
...yes?
[math]\frac{-2}{-4} = \frac{(-1)(2} {-1}{4} = \frac{-1}{-1} \frac{2}{4} = (1)\frac{2}{4} = \frac{2}{4}[/math]

[Anonymous No.16011413]

>>16011407
> But why does the - dissapear?
Click the link.

[Anonymous No.16011414]

>>16011411
Wtf does that mean?
2/4 is 0.5
You guys may know math but you are shit a teaching it.

[Anonymous No.16011415]

>>16011413
>Click the link
Not falling for that one

[Anonymous No.16011419]

>>16011415
You really are a moron. Funny, but still a moron.

[Anonymous No.16011506]

I'm having some problems with this assignment. I'm not supposed to actually solve it, I just want to make sure what the hell they're saying here and whether it's right.

[Anonymous No.16011524]

>>16011506
I don't know what you are writing in paint but at some fixed epoch a tenured prof leaves with probability [math]q_t[/math], so stays with probability [math]1-q_t[/math].
At the same time there may be people getting promoted 2 -> t, on average [math]p_2 E(y)[/math].

[Anonymous No.16011552]

>>16011524
The issue I'm having is how can E(z) depend on E(z)? The stuff underlined.

[Barkon No.16011555]

>>16011552
You know the joke. Stop

[Anonymous No.16011570]

>>16011555
What joke? If I wasn't having problems with this shit I wouldn't be posting in this cesspit.

[Anonymous No.16011659]

>>16008621
a=1
b=-1?

[Anonymous No.16011690]

>>16011552
What's wrong with that? It's not 'depending' in any physical way, it's just an equality.
Maybe what you're missing is the fact that you're supposed to be in equilibrium. If you think about it in terms of sequences, you have z_n tenured profs, and then for the next period you'd calculate z_{n+1}=(1-q)z_n+... Because of this equilibrium these will (should) then have the same expectation.

[Anonymous No.16011742]

>>16011690
So I tried looking into what they actually mean by equilibrium and all I got was a bunch of Markov chain stuff. What exactly do they mean, as in, what do I need to read in order to figure out what they want from me?

[Anonymous No.16011769]

What does plasma look like? Im not just talking about arcs of electricity you see in a plasma ball or a very far away glimpse at the sun. I want to know what a cup of plasma would look like in my hand, preferably at temperature where its not glowing red from heat

[Anonymous No.16011798]

>>16011769
>what does plasma look like?
>I'm not talking about [two examples of what plasma looks like]
what are you even asking?
>>16011349
anyone who hypes up the "next big mathematical filter" is doing so because they, at one point, were probably filtered by it and have a load of insecurity surrounding that. tensor products in physics are generally very simple, only used to represent the fact that you have different vector spaces in the problem that only interact with certain properties of your system (i.e. spin+angular momentum for certain problems, or multi-particle systems all having their own independent vector space)

[Anonymous No.16011833]

>>16011798
I want a close up look of plasma, looking at a solid planet from orbit doesnt give a very detailed of what a solid looks like and if all plasma looked like arcs of electricity, the sun would also just look like a round arc of electricity which it doesnt so its clearly not the only form it can take. Whats so hard to understand about that?

[Anonymous No.16011837]

>>16011833
the arcs of electricity in a plasma ball are plasma. "arcs" are plasma.
almost all plasmas are very hot. very hot things emit blackbody radiation, making them very bright. you see the bright light emitted from the hot sun plasma. this is what the plasma looks like.
cold plasmas are very rare but generally just look like diffuse clouds with a color that depends on the material comprising the plasma, but is usually whitish blue

[Anonymous No.16011858]

>>16011837
>cold plasmas are very rare but generally just look like diffuse clouds with a color that depends on the material comprising the plasma, but is usually whitish blue
This is the answer i was looking for. It looks cool, almost ethereal

[Anonymous No.16011872]

If oxygen is attracted to magnets, does that mean running air through a chamber lined with magnets will create an area of higher oxygen concentration?

[Anonymous No.16011879]

>>16011872
https://sciencedemonstrations.fas.harvard.edu/presentations/paramagnetism-oxygen
For gaseous oxygen, the energy of motion in the gas particles and collisions between them would require magnets beyond the scope of what we can use.

[Anonymous No.16011899]

>>16011380
Does attaching a pic of our homework with Spanish/Portuguese instructions work for us native Spanish/Portuguese speakers, or do we need to translate it to an even more exotic language with less speakers, like Saami or Gujarati for the sake of incomprehensibilitymaxxing?

[Anonymous No.16011975]

Let [math]f: V \rightarrow W[/math] be a linear transformation.
a) Prove that [math]\operatorname{ker} f^{*}=(\operatorname{Im} f)^{\circ}[/math].
b) Prove that [math]\operatorname{dim} \operatorname{Im} f=\operatorname{dim} \operatorname{Im} f^{*}[/math].
c) Conclude that the row rank of a matrix is equal to its column rank.

Could you help me with c?
I said that the column rank can be seen as [math]dim (Im\ f)[/math], and that the row rank can be seen ass [math]dim (Im\ f^\ast)[/math].
So using b they are equal.
But I feel like if I didn't completely understand it, like the way I say it is too vague. Do you think is fine or could you come across with a more formal proof?

[Anonymous No.16012014]

Got a decent hold on Organic should I follow with Inorganic(Miessler) or Physical(McQuarrie)? I could also spend some time with Fleming's book on Orbitals if the extra time with Organic is Vital.

[Anonymous No.16012082]

Is it correct to state the first isomorphism theorem for vector spaces as
>Let [math]\varphi\in\mathcal{L}(V,W)[/math] Then [math] V/\mathrm{ker}(\varphi)[/math] is isomorphic to [math]\mathrm{im}(\varphi)[/math]
?

[Anonymous No.16012100]

Re-writing in matrix forms... How did they go frok 10.11 to 10.12 and then in 10.14 how is the matrix populated with 2 and 1?

[Anonymous No.16012101]

>>16012100
Here

[Anonymous No.16012105]

>>16012100
>>16012101
There is a second similar example from 10 19 to 10.22

I'm not sure what matrix format accomplishes and I don't know how those matrices are populated with numbers

[Anonymous No.16012115]

>>16011975
(assuming f* means dual map, not adjoint)
It's fine. For more details you can prove that the column [row] rank is the dimension of the span of the columns [rows] of the matrix of f or f* wrt some basis. Then if you show the matrix of f* is the transpose of the matrix of f you're there.

[Anonymous No.16012123]

>>16012101
Can you do it the other way around? Now that you know what the vector U is, and the matrix [m], can you calculate what is 1/2* U^T[m]U ?

[Anonymous No.16012262]

>>16011506
12=8+12/3 is a perfectly valid equation even though it has 12 on both sides. x=8+(x/3) is a perfectly reasonable equation even though it has x on both sides. A=B doesn't mean 'here is a useful way to calculate A if you don't know it', it just means that If you manage to calculate A and B, you'll find they have the same value.

[Anonymous No.16012276]

>>16011191
Totally wrong. There's no guarantee that time doesn't go back forever (it probably doesn't because of the big bang, but it is possible that that's just part of a cycle of expansion and contraction) and even if there was that doesn't say anything about whether or not it goes forward forever, or whether space is infinite.

[Anonymous No.16012280]

What am I doing wrong?

[Anonymous No.16012285]

>>16012280
Set the polynomial equal to 0, plug in the roots and you'll have two equations and two variables. Then you just solve the linear system you find

[Anonymous No.16012306]

>>16012285
Something like this?

[Anonymous No.16012309]

>>16012306
Take a root, plug in the x place. You'll have an equation in two variables.
Do the same thing for the other root. Then you'll have two equations and two variables.
Btw you should be 18+ to post here

[Anonymous No.16012312]

>>16012309
Like this?

[Anonymous No.16012313]

>>16012312
Yes. Now you solve this system.

[Anonymous No.16012315]

>>16012313
What now?

[Anonymous No.16012317]

>>16012315
Solve the system.

[Anonymous No.16012319]

>>16012317
How?

[Anonymous No.16012320]

>>16012319
Get the book "Basic Mathematics" by Serge Lang.
Study it.

[Anonymous No.16012321]

>>16012320
I dont have time to read a book. Give the formula and a quick run down and I'll get it. Please

[Anonymous No.16012322]

>>16012321
https://www.khanacademy.org/

[Anonymous No.16012324]

>>16012322
Just tell me how

[Anonymous No.16012333]

>>16012324
You've been told how. It is not our problem if you don't follow the advice. You can't expect people to cram multiple classes worth of knowledge into a single post. Math isn't a subject you can rush or skip steps to learn.

[Anonymous No.16012337]

>>16012333
Something like this?

[Barkon No.16012338]

>>16012333
Trips lady. Hey hon. She spoke

[Anonymous No.16012339]

>>16012338
>>16012333
All you have to do is tell me:
>Do this
>Then this
>Then this and you get the result
If you say so clearly, I'll understand. It really aint that deep

[Barkon No.16012340]

>>16012337
A frenlin rush

[Anonymous No.16012342]

>>16012339
No. It is not our job to be your math teachers. This isn't for /sqt/ is for. What ever test or exam you're trying to pass I am going to be honest with you. The way you're acting right now and what you are doing, you are going to fail and fail badly.

[Anonymous No.16012344]

>>16012342

[Anonymous No.16012400]

>>16012319
Anyone?

[Barkon No.16012401]

>>16012344
A joke, for you

[Anonymous No.16012415]

>>16012319
Please, the book I'm working with tells me how to solve a but then at the end gives me exercises to solve about b when they didnt say anything about b the whole chapter.
Just tell me how. If I ask here its because I can find it on google
Anyone?

[Anonymous No.16012427]

>>16012401
>>16012342
Nvm, found it
https://youtu.be/SE7ZyEkPkgA?si=0hEJCUG_vOtXXxsF

[Anonymous No.16012471]

The double dual of [math]V[/math] is the space [math]V^{\ast\ast }=\left(V^{\ast}\right)^{*}[/math].
a) For each [math]v \in V[/math], define the function [math]e v_{v}: V^{\ast} \rightarrow \mathbb{k}[/math] given by [math]e v_{v}(\varphi)=\varphi(v)[/math]. Prove that [math]e v_{v} \in V^{\ast\ast}[/math].

Would proving its linearity (addition and multiplication of scalars) be enough?

[Anonymous No.16012477]

>>16012471
Depends what you're studying. Normally [math]X^*[/math] are the continuous linear functionals on [math]X[/math].
If you don't know why continuity is important then probably linearity is enough, yes.

[Anonymous No.16012754]

Anyone here knows what the fuck is
[eqn]\mathbb{R}[x]_{\Big/(x-1)^2} [/eqn]
isomorphic to? I know it's not a field or an integral domain, but I don't know what it is.
(I'm getting filtered by abstract algebra)

[Anonymous No.16012787]

>>16012754
It's isomorphic to the ring of dual numbers. The isomorphism maps x to 1+epsilon.

[Anonymous No.16012960]

>>16005019
>could you guys tell me what did I do wrong? Thank you
if functions are not math

[Anonymous No.16013122]

I have often wondered, do higher than 3-sided polygons have as much crazy mathematical shit going on as circles and triangles do but at a superhuman level?

[Anonymous No.16013218]

>>16013122
If you're talking about ratios in those shapes, there's a lot. Some key ones in the regular heptagon involve a ratio of cubes rather than just squares
But since you can triangulate higher polygons, they're just particular arrangements of the base case.

[Anonymous No.16013314]

>>16012960
They are

[Anonymous No.16013330]

Is "increment" here a typo? I strongly suspect it's supposed to be "differential" but I'm not confident enough with the material to really say if it's a typo or not. The previous page already covered something defined as the "increment" so it would be weird to re-define it here. There are no errata published for the textbook.

[Anonymous No.16013365]

>>16013330
nevermind I'm retarded and I took calc I 6 years ago

[Anonymous No.16013528]

How can you self-diagnose midwittery? So far my personality of researching idiotic questions(sometimes scientific, more often historical) seems to have masked my actual intelligence but then I'm put to an actual logic test(even bitch-basic undergrad level proofs) and I don't do anything of note, or fail the proof not due to a lack of understanding the concepts but failure to use algebra properly.

[Anonymous No.16013550]

For any [math]A \in \mathbb{k}^{n \times n}[/math], prove that [math]B \in \mathbb{k}^{n \times n} \mapsto \operatorname{det}(A)^{-1} \operatorname{det}(A B)[/math] is an [math]n[/math]-multilinear alternating form on the space of columns, which evaluates to 1 on the identity matrix. Conclude that [math]\operatorname{det}(A B)=\operatorname{det}(A) \operatorname{det}(B)[/math].

[Anonymous No.16013555]

>>16013550
I don't get the alternating part. Also, the multilinear part, does it not just follows from the fact that that linear map works with determinants that are multilinear?
The identity part can be shown by just replacing B with the identity and showing that it also gives the identity?
The last part is pretty straight forward too once I got the identity thing btw, but again, what I'm struggling with the most is the alternating part, and that everything seems so obvious if we are working with determinant I don't even know how to phrase the proof if it's not by saying "it comes from working with determinants that are multilinear functions"

[Anonymous No.16013619]

>>16013528
if you are challenging yourself with logic and algebra it sounds like you are doing alright. the best thing you could do is join a community of like minded people. that is actually the main benefit of going to university not all the other bullshit. but there are other avenues too, like your local ham radio club has real engineers in it

[Anonymous No.16013625]

>>16013619
>your local ham radio club
just throwing ideas out there. programming club of some kind is good too. maker space or hacker space is good. chess club is good. any kind of math circles but people might think your a pedophile. not judging here. actually if you have some kind of adult education center you can study languages there. you can pick up chicks (adult) at the same time

[Anonymous No.16013711]

What's the physical interpretation of a pseudo-scalar trivector?
Could electric charge be considered as one?

[Anonymous No.16013719]

>>16013528
Midwits think reading the results of other people's hard work makes them smart. Actual smart people test things IRL.
The physical world is a cruel bitch, and putting ideas into action is always harder than it looks. If you can't bring your shitty backyard project to fruition within 5 years, you are in fact a midwit.

[Anonymous No.16013983]

>>16013711
> Could electric charge be considered as one?
No. Charge does not change under a parity transformation (that requires charge conjugation) and it also has no direction so can't be classed as any kind of vector.

[Anonymous No.16014007]

Is the butterfly effect actually named for the shape of the lorentz attractor or did I hallucinate this information

[Anonymous No.16014019]

>>16014007
Seems like a hallucination. In his original paper he used the anology of a sea gull's wings instead. It was only much later the term butterfly effect was coined.

[Anonymous No.16014029]

How come there's relatively copious literature on breaking N-N(the other N usually being part of a cyclic compound) bonds in hydrazines but none(that I've found at least, maybe my keywords are shit) on doing the same in nitroamines? How do deamination and denitrogenation differ mechanically?

(P.S My question of what exactly M refers to in this image was left unanswered last thread, source is J. Org. Chem. 55, 6219-6223)

[Anonymous No.16014080]

I can't intuitively understand how an optical phonon can scatter against an electron. The former is a collective excitation, the latter is a particle, so it how can it make sense to talk about a collision?

[Anonymous No.16014086]

Tried asking this as a seperate thread but no response.

The first rule of thermodynamics is we don't talk about thermodynamics.

The second law of thermodynamics is equivalent to the statement "Heat flows from hot to cold".

See pic related, here we have a piece of metal that we make really hot until it starts transmitting photons (emitter). We can then place a curtain element in front to block the photons and absorb the light. The gas is equally hot as the emitter, so it can transport heat from the curtain to the rest of the system on one side.

Now by putting the curtain in front of one of the elements, we can transport heat between two equally hot systems.

Therefore as long as the system stays hot enough, which is true when it is isolated, then we broke the second law of thermodynamics.

Wtf? Am I doing something illegal or is this actually possible?

[Anonymous No.16014106]

>>16014019
Thanks, to be fair to myself, I think this is a pretty sensible mistake to make, as much as one can be

[Anonymous No.16014107]

>>16014086
>anon discovers entropy, 2024 colorized
Jokes aside, IIRC this is the exact sort of problem that did lead to research in entropy.

[Anonymous No.16014176]

>>16014086
The "curtain/absorber" must also be an "emitter". Can't have low albedo without high emissivity, at least for photons in the same temperature range.

[Anonymous No.16014270]

>>16013711
>https://en.wikipedia.org/wiki/Triple_product
This is the same thing in more pedestrian language. There are tons of examples where something like this appears. One nice example from ordinary classical physics is the "helicity" of fluid flow
https://en.wikipedia.org/wiki/Hydrodynamical_helicity

[Anonymous No.16014322]

>>16014080
Your confusion arises because it's just a label. There isn't any scattering process actually taking place, but you can treat it as if there is. What is physically occurring is the phonon waves (lattice vibrations) interacting with an already vibrating lattice structure (due to heat).

[Anonymous No.16014356]

>>16014322
>What is physically occurring is the phonon waves (lattice vibrations) interacting with an already vibrating lattice structure (due to heat)
Wait, where is the electron in all of this?

[Anonymous No.16014365]

>>16014356
What do you think a vibrating lattice involves?

[Anonymous No.16014389]

>>16014356
actually mb. if you are talking metals then its the free electrons involved. more heats means more vibrations, which means more phonons and electron interactions. this reduces the mean-free path of the conducting electrons and hence the affects the conductivity.

[Anonymous No.16014587]

>>16004276
Does aftershave actually reduce or prevent razor bumps?

[Anonymous No.16014653]

What am I doing wrong? One of the solutions is supposed to be 1 or -1 but I get 0.

[Anonymous No.16014719]

>>16014653
Either you've fucked up earlier in your work or there's a problem with the question itself, because all of the work you've shown here is fine. There's no way to reduce the system shown to the only solutions being 1 or -1. In fact, you've shown that ANY x gets you a valid solution, because the two equations describe the same curve

[Anonymous No.16014728]

>>16014719
So its just an error?

[Anonymous No.16014749]

So pretty much the assignment is to make a program that gives you back change as though it's a vending machine, Bitcoin should be equal to 75c, Doge 38c, Eth 12c and Pennies 1c based on your input, which should be less or equal to 100. I'm just not sure where I'm going wrong in my code, because it looks like I am following along with the textbook.

[Anonymous No.16014753]

>>16014749
Oh nvm I am retarded I am gonna delete this as soon as I can

[Anonymous No.16014779]

>>16014029
>How come there's relatively copious literature on breaking N-N... bonds in hydrazines but none... in nitroamines?
idk
>(P.S My question of what exactly M refers to in this image
metal alkali substitution. commonly grignard, organozinc, organocuprate etc.

Try looking for "acyl hydrazide reduction" or something similar

[Anonymous No.16014826]

>>16014728
Yes that's an error. The two equations are not independent. Multiply the first equation by -12 and the second by 2 and you get identical equations.

Also the given answer doesn't even work if you plug in the values for x and y.

[Anonymous No.16014887]

>>16014176
Sure but there is still a way to achieve the same result with perfect mirrors.

See pic related, here we try to rotate the emitter so that it increases the relative area of emission to the other system. I think we can even remove the gas.

[Anonymous No.16014899]

If x,y, and z are real numbers such that x^2 + y^2 + z^2 < xy + xz + yz,

prove that x + y + z > 0

[Anonymous No.16014908]

>>16014270
aren't electrons helical? I vaguely remember susskind saying that

[Anonymous No.16014922]

>>16014908
Helicity in particle physics is the projection of spin in the directon of momentum. It's a completely different concept with no relation. If you really want to make a connection to high energy physics language, fluid-mechanical helicity is basically the same thing as a U(1) Chern-Simons term (where the fluid velocity is understood as a vector potential).

[Anonymous No.16014925]

>>16014922
>projection of spin in the directon of momentum
what's that in english? the magnetization is aligned in parallel with the velocity?

[Anonymous No.16014929]

>>16014925
Yes

[Anonymous No.16015042]

>>16014899
>x^2 + y^2 + z^2 < xy + xz + yz
Not possible. That inequality is never true.

[Anonymous No.16015324]

>>16014587
also, does dog/cat food cause cancer? it seems like most of the dogs and cats my family has owned have died of cancer. my current doggy has mouth cancer, and that makes me think that it might have to do with the food that we were feeding her. maybe I'm just paranoid, but it just seems wrong that all of my furry loved ones have had to go this way.

[Anonymous No.16015841]

new thread: >>16015839