/sqt/ stupid questions thread

[Anonymous No.9729480]

This thread is for questions that don't deserve their own thread.
>give context
>describe your thought process if you're stuck
>try wolframalpha.com and stackexchange.com
>How To Ask Questions The Smart Way http://www.catb.org/~esr/faqs/smart-questions.html

prev >>9714560

[Anonymous No.9729510]

I really really like this picture

[Anonymous No.9729537]

>>9729510
anyone have the edit?

how do i show pic related? idk if im making a simple mistake in the algebra or im approaching the problem in completely the wrong way.
so far ive got
[math] \dot{x}=x-y-(x^2+y^2)x\\ \dot{y}=x+y-(x^2+y^2)y [/math]
letting [math] x=r\cos\theta [/math] and [math] y=r\sin\theta [/math] gives
[math] \dot{r}\cos\theta-r\dot{\theta}\sin\theta=r\cos\theta-r\sin\theta-r^3\cos\theta\\ \dot{r}\sin\theta+r\dot{\theta}\cos\theta=r\cos\theta+r\sin\theta-r^3\sin\theta [/math].
then
[math] \dot{r}\cos\theta\sin\theta-r\dot{\theta}\sin(\theta)^2=r\cos\theta\sin\theta-r\sin(\theta)^2-r^3\cos\theta\sin\theta\\ \dot{r}\sin\theta\cos\theta+r\dot{\theta}\cos(\theta)^2=r\cos(\theta)^2+r\sin\theta\cos\theta-r^3\sin\theta\cos\theta [/math]
adding
[math] 2\dot{r}\sin\theta\cos\theta=r(\cos(\theta)^2-\sin(\theta)^2)+2r\cos\theta\sin\theta (1-r^2)[/math]
but i dont know where to go from there

[Anonymous No.9729544]

>>9729537
try doing [math]\sin\theta x' - \cos\theta y'[/math]

also, what edit?

[Anonymous No.9729737]

Is IQ real?

[Anonymous No.9729773]

anyone know how to answer this?
i know that I has to be a maximal ideal, but idk what "necessary" and "sufficient" mean in this context

[Anonymous No.9729793]

>>9729773
>i know that I has to be a maximal ideal, but idk what "necessary" and "sufficient" mean in this context
necessary and sufficient means equivalent, so you would want to show that R/I being a field means I is maximal, and that I being maximal means R/I is a field

[Anonymous No.9729809]

>>9729737
>Is IQ real?
Yes.

[Anonymous No.9729812]

Are there any other factors that can induce the placebo effect?

[Anonymous No.9729813]

>>9729737
No.

[Anonymous No.9729853]

How tf do i do this? getting 15 for part a and 13 for part b, but both should be equal

[Anonymous No.9729858]

>>9729853
>How tf do i do this? getting 15 for part a and 13 for part b, but both should be equal
Show your work.

[Anonymous No.9729929]

>>9729858

[Anonymous No.9729937]

>>9729858
>>9729929

[Anonymous No.9729941]

>>9729937

[Anonymous No.9729989]

A single card is being drawn.

What is the probability of choosing a heart or not a queen?

[Anonymous No.9729993]

>>9729989
Isn't it 49/52. Everything except the queen of spades, queen of diamonds, and queen of clubs?

[Anonymous No.9730011]

>>9729737
>tfw IQ is 90+150i

[Anonymous No.9730157]

Brainlet here. Can someone help me differentiate between Sn1, Sn2, E1 and E2 reliably?

I know what they all do (roughly) but Sn2 vs E2 and Sn1 vs E1 are tricky.

if I don't get many replies here I'll just make a thread

[Anonymous No.9730177]

Can someone help me with these two problems?

[Anonymous No.9730183]

You roll 3 dice. What is the probability of rolling at least 2 sixes?

I keep getting 16/216 but I'm told that's wrong.

[Anonymous No.9730194]

>>9730177
are you using avocado's number correctly?

[Anonymous No.9730200]

>>9730194
You just multiply the number of moles by avacados numbers to obtain atoms/ions, right?

[Anonymous No.9730258]

>>9730200
as far as I know, yeah. Check your dimensional analysis for each problem and see if that's where you slipped up. Weird that you didn't even get partial credit?

[Anonymous No.9730267]

>>9730183

Who is telling you that's wrong?

[Anonymous No.9730272]

>>9729937
so basically you want the odds of not choosing the queen of spades, clubs, or diamonds. it's 49/52

[Anonymous No.9730273]

>>9730267
This math practice website. It's maddening because I can't understand how it's wrong, are you saying the site's mistaken?

[Anonymous No.9730276]

>>9730183
simplify the fraction

[Anonymous No.9730287]

>>9730177
your formula is wrong. It's CaBr2 not Ca2Br
the equation should be
3.16E22 Ca ions * (1 mol Ca / 6.022E23 Ca ions) * (2 mol Br / 1 mol Ca) * (6.022E23 Br ions / 1 mol Br) = 6.32 E 22
notice it's just double the amount of Calcium since there are two bromide ions for every calcium ion

Notice that your answer is half the given. What you did is the same, except you put 1 mol Br for every 2 mol Ca.
Also, the molar mass is irrelevant for this problem since it's only asking about ion number.

[Anonymous No.9730292]

>>9730276
Tried that, it changes nothing.

[British isles No.9730293]

What is k space in physics?
What is positional space in physics?
What is space in general in physycs?
How many spaces are there?
How does Fourier conversion relate to subatomics?
What are fields in relation to that and in relation to basic quantum mechanics?

I used to think that subatomic particles were really just areas where a rule would be in effect, where that rule would be an individual wave function. And its determinative as in the probability of the wave function being present at a certain point.

[Anonymous No.9730294]

>>9730183
1/6 * 5/6 * 5/6 + (5/6)^3 = 25/36 this is the probability of getting either 0 sixes or 1 six.
1-ans = 11/36

[Anonymous No.9730619]

math genii only:

How do you prove that

$$\frac{3n^3+2n^2+n}{5n^3-6n+7}$$ has a limit of $$\frac{3}{5}$$

using the definition of a limit (epsilon and delta or N)

[Anonymous No.9730691]

>>9730294

Missing a term there.

>>9730273

You are right; the correct answer is
(3 choose 2) (1/6)^2 (5/6) + (1/6)^3 or alternatively 1 - (5/6)^3 - (3 choose 1)(1/6)(5/6)^2 = 16/216.

[Anonymous No.9730700]

>>9730619
>How do you prove that
>$$\frac{3n^3+2n^2+n}{5n^3-6n+7}$$ has a limit of $$\frac{3}{5}$$
>using the definition of a limit (epsilon and delta or N)
What have you tried?

[Anonymous No.9730718]

>>9730700
I have shown that it is less than $$ < \frac{2n+5}{5n^2-6} < \epsilon$$ but I can't get any further

[Anonymous No.9730738]

Why are explanations of a centrifugal force always couched in terms of a rotating reference frame. Is it simply for illustrative purposes?

Consider a free body diagram of a weight swinging in a circle around a fixed point on a cord. There is a force vector from the weight, pointing towards the center, this is the centripetal force. Owing to Newton's third law, there is an equal and opposite force pulling on the center point in the other direction. Is this not the centrifugal force without needing to evoke a rotating reference frame?

[Anonymous No.9730780]

>>9730294
This is intuitively wrong, there's no way you have an almost third chance to get 2 sixes.

[Anonymous No.9730782]

>>9729537
Dont forget x^2+y^2=r^2

[Anonymous No.9730805]

>>9729812
regression toward the mean

[Anonymous No.9730853]

What is this fucking symbol for? It's my understanding it's some kind of integral over a closed volume, but I can't find anything about it online. Can someone post or link an example? I've been tormented by this since I took calc 3.

[Anonymous No.9730895]

how much harder is diff eq than calc 3? i just finished calc 3 and i had to study way fucking harder than i ever had in calc 1 or 2 and its my understand diff eq is even harder. i really had to study for a long time with basically every calc 3 concept, before i was able to understand it: fundamental theorem of calculus, rewriting bounds of integrals, building normal vectors to surfaces, interpreting curl/divergence. i still made a really good grade but i studied for hours upon hours

as a side note, why do people act like calc 2 is way harder than calc 3 or diff eq? i barely had to study in calc 2 and i made an A. do europeans have way harder versions of calc 2 or something?

[Anonymous No.9730905]

>>9730895
It depends on the teacher, my calc 3 teacher was kind of dumb so it was an easy A. I took calc 2 over the summer in an 8 week course and got an A, it wasn't too difficult, but it was definitely a bit harder than calc 3 for me.

[Anonymous No.9730948]

Why does pic-related not converge?

Isn't (n+3)/(n+1) monotonically decreasing?

[Anonymous No.9730951]

How do you prove the pic-related diverges?

[Anonymous No.9730954]

>>9730951
it's an alternating series but |a_n|>1

[Anonymous No.9730963]

>>9730954
Does that imply it diverges? Can you elaborate a little more?

[Anonymous No.9730989]

>>9730963
|a_n - a_{n+1}|>2 for all n

[Anonymous No.9730993]

>>9730805
Elaborate pls

[Anonymous No.9731000]

>>9730989
I kinda get that, but I don't see how it shows that it diverges (by the Alternating Series test or something)

One way I see to prove it diverges is to show that the limit of the summand is not 0 using delta and epsilon, but that needs like it's overly tedious

[Anonymous No.9731006]

>>9730951

plug in any number for example 5 for n then n is -4/3 and for n+1 it is 9/7 |-4/3 - 9/7| = 55/21 = greater than 2

hes saying that when u take the difference of whatever number u plug in for n and its n+1 evaluation, it will always be greater than 2.

[Anonymous No.9731007]

>>9730951
Ratio test

[Anonymous No.9731051]

>>9731007
Thank you!

[Anonymous No.9731053]

>>9731007
Doesn't that only work for sequences with all positive terms?

[Anonymous No.9731101]

how do I approximate the solution to a cauchy problem y' = -2xy, y(0) = 1

when i plug it into pic related I get an expected first approximation y = 1 - x^2 but I can't figure out the next approximations.

the real answer should be the taylor expansion for e^(-x^2)

[Anonymous No.9731106]

>>9731053
No

[Anonymous No.9731112]

>>9730951
Nevermind I managed to prove it by contradiction (show that the summand does not have a limit of 0).

[Anonymous No.9731114]

>>9731101
actually i think i figured it out

[Anonymous No.9731172]

Does Gödel's incompleteness theorem affect physics? I.e. are there always phenomena (analogous to mathematical truths) that we can't explain with our physical principles (analogous to axioms)?

[Anonymous No.9731362]

What is the "rotation matrix" i have to use if i want to skew the two axis of a plane with different angles?

Ie: from the basic cartesian plane, i turn the X axis n1 degrees and the Y one n2 degrees from their original positions
Let's assume i turn the X axis 10° "inwards" and the Y axis 45° inwards so the angle between them ends up being 35° for the sake of argument.

What would be the "generalized" version? I tried but it's a clusterfuck and i hardly think it's correct

[Anonymous No.9731375]

>>9730853
the circle is usually superfluous

it usually just signifies that the integral over the set you're taking it is in fact a closed surface

[Anonymous No.9731378]

>>9731172
yang mills mass gap possibly undecidable

[Anonymous No.9731390]

>>9730157

[Anonymous No.9731404]

>>9731362
>What is the "rotation matrix" i have to use if i want to skew the two axis of a plane with different angles?
>Ie: from the basic cartesian plane, i turn the X axis n1 degrees and the Y one n2 degrees from their original positions
>Let's assume i turn the X axis 10° "inwards" and the Y axis 45° inwards so the angle between them ends up being 35° for the sake of argument.
Treat them independently and then make (First rotation matrix) * (Second rotation matrix)

[Anonymous No.9731411]

>>9731404
From what i can understand from Wikipedia, the product of two rotation matrices is still a rotation matrix, hence resulting in the "sum" of the various rotations but still keeping the angle between the x and y axes at 90°.
What i'm looking for is to end up with a x' and y' axes that are not at 90° from each other.

[Anonymous No.9731428]

>>9731411
>What i'm looking for is to end up with a x' and y' axes that are not at 90° from each other.
That cannot be done with a rotation matrix, as they preserve orthogonality of the axis.

What you can use is directly use something like
[math] \left(\begin{array}{c}
\cos \phi_x & \cos \phi_y\\
\sin \phi_x & \sin \phi_y
\end{array}\right) [/math]

[Anonymous No.9731449]

I'm an autist so remind me

1 degree is 60 minutes, so 1°30' +1°30' = 3°right?

[Anonymous No.9731459]

>>9731428
Yeah that is what i was thinking, however it ended up being a clusterfuck and three quarters.
I started from the first arbitrary base being B={[a,b];[c,d]} and the second base being D={[a*cos(n1), b*sin(n1)];[c*sin(n2);d*cos(n2)]}, found the Mb<-d (the matrix that brings you from D to B) as (don't know TeX)
1/cos(n1) 1/sin(n2)
1/sin(n1) 1/cos(n2)

Clusterfuck soon followed

[Anonymous No.9731499]

>>9731449
Yes. Since 60 minutes is 1 degree, 30 minutes is half a degree.

[Anonymous No.9731512]

>>9729537
You can rewrite the equations in your pic as:
[math]
\frac{d}{dt} (x+y i) = (1-r^2+i)(x+yi) = (1-r^2+i) r e^{i\theta} = r(1-r^2) e^{i\theta} + r i e^{i\theta}
[/math]
Also,
[math]
x+yi = r e^{i\theta} \implies \\
\frac{d}{dt} (x+y i) = \dot{r} e^{i\theta} + r \dot{\theta} i e^{i\theta}
[/math]

Therefore:
[math]
r(1-r^2) e^{i\theta} + r i e^{i\theta} = \dot{r} e^{i\theta} + r \dot{\theta} i e^{i\theta}
[/math]

Since [math] e^{i\theta} = (\cos\theta,\sin\theta) [/math] and [math] i e^{i\theta} = (-\sin\theta,\cos\theta) [/math] are always linearly independent we get:
[math]
r(1-r^2) = \dot{r} \text{ and } r=r \dot{\theta}
[/math]
Cancel r in the last equation and you get what you want.

[Anonymous No.9731526]

>>9730183
You may roll exactly 2 sixes (event A), or you may roll exactly 3 sixes (event B); both are acceptable and they are the only acceptable ones.
A and B are disjoint events, therefore [math] P(A \cup B) = P(A) + P(B) [/math] .
Both P(A) and P(B) are texbook binomial distribution examples.
[math]
P(A) = \binom{3}{2} (\frac{1}{6})^2 (\frac{5}{6})^1 = \frac{5}{72} \\
P(B) = \binom{3}{2} (\frac{1}{6})^3 (\frac{5}{6})^0 = \frac{1}{72}
[/math]
Therefore, [math] P(A \cup B) = \frac{6}{72} =\frac{1}{12} [/math]

[Anonymous No.9731528]

What should I buy in order to start making pyrotechnics?

[Anonymous No.9731530]

>>9731362

figure out where it takes the standard basis and then take the inverse. if you want to parameterize this with rotation angles, then apply individual rotation matrices separately to each basis vector.

[Anonymous No.9731531]

>>9731526
typo: [math] \binom{3}{3} [/math] for P(B), not [math] \binom{3}{3} [/math] .

[Anonymous No.9731626]

What are hybrid orbitals??

[Anonymous No.9731804]

>>9731626
Are you supposed to mention the d orbitals that both have?

[Anonymous No.9731864]

sorry if this is the wrong place for this but I wasn't sure this warranted a new thread of it's own.

I had an idea that I'd like to know more about and was wondering if anyone can tell me what it's called.
https://www.youtube.com/watch?v=gM6QkPsA2ds
I was wondering if our universe operates under the same principal as the Euclideon game engine. Basically the game engine pre-renders everything as a point cloud where each point is like 1 atom. It creates the display using something kind of like a search engine, where if your display is 800x600 it'll use the search engine to calculate which atoms are to be displayed. But you're only observing or interacting with those 800x600 atoms at a time. Processing time is always the same no matter what's on the 800x600 screen, but processing time will go up as you increase resolution because you're now searching for more atoms/cloud data points to display.
Is this a valid analogy for how our universe works? Could the universe have all it's data stored in a multi-matrix of sorts and our consciousness extracts observable data from this matrix using a similar search algorithm? What does that mean when we try to increase our awareness or increase how much we observe from the universe?

[Anonymous No.9731908]

>>9731804
The question only asks for the central atom.

[Anonymous No.9732004]

>>9731626
Hybrid orbitals are formed when two different orbitals (like s and p) "blend" together to form a new, hybrid orbital.

With the concept in mind that different orbitals have different shapes, sp3, for example, means that one orbital s (which is in fact the only one that exist) and three orbitals p form 4 [1s+3p] identical orbitals.

Here stuff gets a little more complicated, because in those molecules hybrid orbitals involve orbitals that are completely empty in the central atom's electronic configuration: the d orbitals (as >>9731804 correctly said).

The answer is, for both molecule, sp3d.
You can check the theory for the reason, and maybe come back later with more questions.

[Anonymous No.9732239]

Want to improve my knowledge of Trig, have studied it before but need a refresher before calc. What's an advanced book that goes through basically all the trig you'll ever need to know?

[Anonymous No.9732636]

Trying to prove that [math]r(P_3,K_3)=5[/math], don't really need help with the proof, but I have to show that [math]K_4[/math] doesn't contain a path of 3 or a 3 cycle, but I just can't see it.

[Anonymous No.9732714]

Can someone expand on my answer?
Explain/analyze what happens with the current in a circuit that has inductors, from time t=0 to a long time after.

Current increases in the inductor, which also creates a self-induced emf. The current increases over time until it reaches its max, which is given by the equation Imax = V/R * (1 - e^(RT/L)).

I don't know what else to say, but I feel like there should be more to this.

[Anonymous No.9732773]

Is there any difference between these two symbols? Specifically, is one used for the Lagrangian and one for Laplace transforms? When handwriting should I just use a simple capital L for both the Lagrangian and Laplace transforms?

[Anonymous No.9732806]

>>9732714
> The current increases over time until it reaches its max, which is given by the equation Imax = V/R * (1 - e^(RT/L)).
Uh, no. Imax=V/R. I(t)=V/R*(1-e^(-Rt/L)).

[Anonymous No.9732831]

>>9732773
There's no standard encyclopedia for this kind of thing, it's whatever the author has defined it as.

When handwriting you should make your symbols as distinct as they need to be for you to remember them.

[Anonymous No.9732858]

>>9732806
Ok, so I could re-write that to say current increases at a rate of I= V/R * (1 - e^(RT/L)), until it reaches its max of I = V/R
Is that pretty much all there is to say?

[Anonymous No.9732905]

>>9729480
What do you guys think of absement ?

[Anonymous No.9732952]

What would mathematicians like Terence Tao do if they never did mathematics in terms of jobs?

[Anonymous No.9732955]

>>9732858
That's the second time in a row you forgot the negative sign in the exponent.

[Anonymous No.9733086]

I need someone to point me to the right direction.
I have no discipline and no willpower that is greater than a hour a day
I also have time management issues.
There should be books that can give me ideas on how to start being useful to myself.
Where do I start?

[Anonymous No.9733088]

>>9733086
>There should be books that can give me ideas on how to start being useful to myself.
There aren't, you're a lost cause.

[Anonymous No.9733095]

>>9733088
Fuck you as well kid.

[Anonymous No.9733096]

>>9729737
Yes
A better question would be: is it useful?
It's not.

[Anonymous No.9733109]

>>9733095
>Fuck you as well kid.
Do you need to swear?

[Anonymous No.9733249]

How do I get rid of boils on my butt?

[Anonymous No.9733296]

Super Brainlet here. How do I re-study math? Ever since HS (eight years ago) I have forgotten every single thing there is. I can't even multiply anymore to the point I need to use my fingers.

[Anonymous No.9733320]

>>9730853
[math]\Oint[/math] is a integral along a closed Path/Line inside a space with dimension >1

[math]\Oiint[/math]is a integral on a closed surface inside a space with dimension >2

[math]\Oiiint[/math] is a integral on a closed 3-manifold, inside a space with dimension >3.

The extra dimension beyond height/width/depth can be for example: time, temperature, density, electrical charge, energy concentration, etc.

[Anonymous No.9733323]

>>9733320
∮ is a integral along a closed Path/Line inside a space with dimension >1

∯ is a integral on a closed surface inside a space with dimension >2

∰ is a integral on a closed 3-manifold, inside a space with dimension >3.
>https://en.wikipedia.org/wiki/3-manifold

The extra dimension beyond height/width/depth can be for example: time, temperature, density, electrical charge, energy concentration, etc.

[Anonymous No.9733326]

>>9730853

∮ is a integral along a closed Path/Line inside a space with dimension >1

∯ is a integral on a closed surface inside a space with dimension >2

∰ is a integral on a closed 3-manifold, inside a space with dimension >3.
>https://en.wikipedia.org/wiki/3-manifold

The extra dimension beyond height/width/depth can be for example: time, temperature, density, electrical charge, energy concentration, etc.

[Anonymous No.9733514]

>>9732952
kill themselves

[Anonymous No.9733516]

>>9733296

[Anonymous No.9733534]

I got a question: why do the mods sit back and do fuck all while /pol/ shits up this board on an hourly basis?

[Anonymous No.9733771]

>>9733534
They act based on reports as far as I can tell, and 4channers aren't really reporting people.

[Anonymous No.9733993]

with a hash function, it takes an input of arbitrary size and gives an output of fixed size.

Doesn't this mean multiple plaintexts will hash to the same thing.

Say I hash "sjht8245yuwohrtwkj5h0234u2904u" to "AAAAAA" , more characters in the first term.

[Anonymous No.9734041]

>>9733993
>Doesn't this mean multiple plaintexts will hash to the same thing.
Yes.

[Anonymous No.9734422]

Can someone check my work? I’m trying to find the net Ey component of the electric field at point P

[Anonymous No.9734429]

>>9734422

[Anonymous No.9734447]

Are there capsuleless viruses?

[Anonymous No.9734586]

Can someone explain to me how am I supposed to draw curves in the phase space given a potential function?
Like say I have the potential function
[math]
V(x) = \frac{2}{x^2} - \frac{x^2}{2} + 5 \ln x
[/math]
where x>0.
Given the plot of V (pic related), how do I plot the orbits in the phase space?? (axes [math] x [/math] and [math] \dot{x} [/math] )

[Anonymous No.9734599]

Why is it so difficult to find a clear explanation how to turn a general set of chemical reactions i.e. [eqn]\left\{\sum_{j=1}^{m}a_{i,j} x_j \longrightarrow \sum_{j=1}^{m} b_{i,j} x_j \right\}_{i=1}^{n}[/eqn] (with a_{i,j} b_{i,j} coefficients and x_j chemical species) and produce a set of differential equations? Every explanation I've found is a specific example that doesn't seem to give the whole picture.

[Anonymous No.9734609]

>>9730183

These types of "lower-dimensional" problems are quite nice to visualize geometrically. For this specific problem you could imagine a 6x6x6 cube, where each individual minicube corresponds to a possible outcome. The marked pieces on the edges correspond to "at least 2 sixes". There are 16 of them, so yeah, 16/216 is correct.

[Anonymous No.9734628]

>>9734609
The correct answer is here >>9731526 and it is 1/12.
Although calculating it using a cube works, you probably double/triple counted some cubes.
Consider the simpler anologous case: 2 dice, at least 1 six.
Make a 6 by 6 grid.
if you count the bottom row (6,i) where i=1,..,6 and the rightmost column (i,6) where i=1,...,6 , then you can just add 6+6; the bottom right corner (6,6) has been counted twice.

[Anonymous No.9734631]

>>9734628
>then you can just add 6+6
meant "can't"*

[Anonymous No.9734654]

>>9734599
Actually I think I had it, but just ran into some dumb-dumbs out there that made me think I was wrong.

Does this seem right?

[Anonymous No.9734752]

Is this correct?
How many oxygen atoms present in 6.418g of Fe(NO3)3?

Molar Mass = 241.88

(6.418g /241.88 (g/mol) * (9mol O / 1 mol Fe(NO3)3) * (6.022*10^23)

= 1.43 x 10^23 O Atoms

[Anonymous No.9734793]

>>9734752
never mind, just found the answer

[Anonymous No.9734819]

>>9734793
what

[Anonymous No.9734899]

Will getting a PhD in a foreign country make me look like shit to US companies? I am a US citizen with a US bachelors and it would be a top university in said foreign country

[Anonymous No.9734902]

why is psychology so accepted in academia? it is pure sophistry

[Anonymous No.9734908]

>>9734899
It really depends on the country you're going to and whether your field has region-specific knowledge involved. Overall I would say it's moderately less desirable but for many fields and many countries (mostly in Europe, I would say) it doesn't make any difference.

[Anonymous No.9734915]

>>9734908
I am in electrical engineering (optoelectronics) and was thinking of European countries, maybe something like Italy or France.

[Anonymous No.9734943]

How do I become a tech wizard and can figure put math stuff when I'm low iq?

[Anonymous No.9734952]

>>9734943
Fuck off white boy

[Anonymous No.9735020]

Alright, for my master thesis I may have to learn QFT quite fast, so i need advice. The problem is that i will have a limited period of time to do so.

By the time I will have to learn it I will be confortable in non field-related (un-)relavistic qm (density matrix, 2nd quantification, collisions theory, symmetries, dirac equation, etc...). As for classical mechanics and mathematics, I suppose that my level will be sufficient (except of course in advanced topics such as topology or markovian mechanics but i don't expect to need those).

So i'll have 2-3 weeks, my program is that I first plan to get myself confortable with special relativity (my actual level of knowledge of it is introductory) like 2-5 days of intense rushing in this matter. Then I'll start self-teaching QFT with the remaining time. My question is then :

-Is there any kind of mooc/youtube video/blog that will permit me to get an indermediate level of this topic ?

-As for the books, which are the best for self-teaching ? I was recommanded "Quantum field theory in a nutshell" by Zee, but "quantum field theory for the gifted amateur" by lancaster and "quantum field theory and the standard model" by schwartz seems reasonable choices to be followed by Weinberg. What do you think are the best duet for an introduction/reference book combo ?

-Do you think it is possible ? Is my program good ? What are some tips that you can provide me ?

[Anonymous No.9735069]

>>9734902
because it would mean kicking out 80% of female STEM students out of STEM

[Anonymous No.9735249]

Should I use my PhD tuition waiver to take language courses? I've always wanted to learn a new language

[Anonymous No.9735258]

>>9735249
Why do you need to spend money/take a class on something like learning a new language? Aren't there plenty of resources online and books at the library for something like this?

[Anonymous No.9735275]

Whats my net ionic equation supposed to be?

[Anonymous No.9735277]

>>9735275
Since HF is a weak acid, it shouldn't break up. So should my molecular equation be
HF(aq) + KOH(aq) -> HF(aq)+ KOH(aq) ?
There's no net ionic equation because no reaction happens?

[Anonymous No.9735334]

I'm trying to prepare for calc 3 summer course at the moment and am kind of stagnating on the vector functions. Should I move on to partial derivatives and triple integrals or am I better off mastering the vector stuff and going in blind on derivative/integration.

[Anonymous No.9735363]

>>9735275
--> KF + H2O or K+ + F- + H2O. You forgot the salt. Don't listen to >>9735277

[Anonymous No.9735500]

How the FUCK should I ask a professor to be an undergraduate research pleb? I really need this to move forward but I am worried that if I just email it may not go through or may look shit compared to in person even though semester is over by now. I feel like I wouldnt even know what to do in the position anyways as it is some weird shit that I havent even had classes about yet. Please help /sci/ I need you now more than ever

[Anonymous No.9735548]

>>9730287
jfc dude why would you even bother with molar mass, they give you the number so just multiply by the ratio

[Anonymous No.9735559]

>>9730293
k space is momentum space, it's usually in reference to a wavevector as in f(r) = exp[i*k . r]
positional space is typically your usual 3d space, except with multiple particles in which case it's 3 * N dimensional
spaces are vector spaces. There are lots of them, anything that is a vector lives in a space.

Fourier transforms take your wavefunction from momentum to position space. Fields are things that have values for each point in space or time, whether that value is a vector or scalar or whatever.

Also,
>determinative
>probability
Think about what you just said. Your statement makes no sense.

[Anonymous No.9735632]

I found this in my high school physics book. WTF this means? What are p20 and R20?

Sorry for shitty translation of accompanied text.

[Anonymous No.9735638]

>>9729480
how do we know that black holes exist??

[Anonymous No.9735640]

>>9735500
i got a summer research scholarship. i did it just by asking abou 5 or 6 different professors in person (visitng their offices) until one of them said yes

[Anonymous No.9735643]

>>9733534
i agree

[Anonymous No.9735647]

>>9735632
the p is the greek letter rho and the a is an alpha
the 20 i assume signifies room temperature resistivity then the alpha is just a constant. those equations just scale the temperature up from the room temperature interestingly enough
[math] \rho = \rho_{20} + \beta \Delta T [/math] where [math] \beta = \rho_{20} \alpha [/math]

[Anonymous No.9735648]

>>9735647
thank you <3

I dont understand why they could not say that anywhere in the book :)

Have a picture of puppy as payment

[Anonymous No.9735653]

>>9735632

It is a constant caracterised by the resistance (and resistivity) of your thermoresistance at 20°C .

More info : https://en.wikipedia.org/wiki/Resistance_thermometer

[Anonymous No.9735686]

I have been reading this so many times but I just do not get what is different about L1 and L2 regularization.

How can summing absolute values of weights give a different result from summing squares of weights? The absolute values are all positive, so weights can not just cancel out and be set to zero, the same applies to squares.

[Anonymous No.9735781]

>>9729510
same
ed witten is a god

[Anonymous No.9735798]

>>9735686
They both stop weights from getting too big (in absolute value), but they do so differently: The L2 loss is dominated by the big weights (which means small weights don't matter much, and aren't changed much either, even if useless), while L1 loss values the weights more equally.

Consider a simple example with two features which share almost the same information, with one of them having slightly more information (e.g. the less informative one just consists of random noise in 5% of the cases). With L2 regularization, the weights of the features would be almost the same, with the more informative one having slightly higher weights (since [math]w_1^2 + w_2^2 < (|w_1| + |w_2|)^2 [/math] for [math]w_1 \ne 0 \ne w_2[/math]). Meanwhile in the L1 regularization case, it is much more likely that the more informative feature has a high weight and the less informative one has weight 0.

The illustration is also supposed to show this: If the shape of the Loss below a certain value is a rectangle (in the 2D case), the extremum is much more likely to lie on one of the axes than if the shape is a circle (in the 2D case)

[Anonymous No.9735815]

>>9735798
I see, so if it is essentially that by "weighing" the weights with ^2 rather than abs() the contribution to the sum (loss) by smaller weights diminishes then it makes a bit more sense to me
thanks

[Anonymous No.9735842]

>>9734628
even ran a quick simulation, running it 10 times gives me probabilities: (0.07405548, 0.0740586, 0.07409706, 0.07406991, 0.07407746, 0.07401937, 0.07409141, 0.07410235, 0.0740848, 0.07408687)

Looks a lot more like 16/216 = 0.0740740... than 1/12=0.08333...


Source code: (hopefully preserves indentation)
public static void main(String[] args) {
Random r = new Random();
for (int k = 0; k < 10; k++) {
int counter = 0; // counts the number of cases with >=2 sixes
int total = 100000000; // 100 million "triple rolls"
for (int i = 0; i < total; i++) {
int tmp = 0; //counts the number of 6's
for (int j = 0; j < 3; j++) {
if (r.nextInt(6) == 5) { //nextInt(6) gives 0,1,2,3,4, or 5
tmp++;
}
}
if (tmp >= 2) { // at least 2 sixes
counter++;
}
}
System.out.println((double) counter / total);
}
}

[Anonymous No.9735845]

>>9735842
Easier to read

[Anonymous No.9735915]

Again my high school physics book is missing some explanations. What is the alpha angle here?
>Ac voltage

[Anonymous No.9735966]

>>9735915
look at how sin behaves

you (should) know that sin has period 2pi

but in your graph, the period is T, which represents a period of time t.

So sin a is a function of t, that is a=a(t), and since the period doesnt change with time, you can deduce a is a linear function of t, that is, a(t)= ct+d. You know that a(T)=2pi and a(0)=0, so d=0 and c=2pi/T.

So sin a = sin (2t pi / T)

[Anonymous No.9735972]

>>9735966
Ah thank you. I had some idea it had to some how be connected to the phase but it was unclear if alpha had deeper meaning.

[Anonymous No.9736087]

How would I evaluate the improper integral [math]intsin^{n}xdx[/math] ? I tried using integration by parts but I'm still left with an integral.

[Anonymous No.9736088]

>>9735842
You are right, it is 2/27.
>>9731526 put P(B) = [math] \binom{3}{2} (\frac{1}{6})^3 (\frac{5}{6})^0 [/math] instead of [math]P(B) = \binom{3}{3} (\frac{1}{6})^3 (\frac{5}{6})^0 [/math] in the calculator.

[Anonymous No.9736096]

How would I evaluate the indefinite integral [math]int sin^{n}xdx[/math] ? I tried using integration by parts but I'm still left with an integral.

[Anonymous No.9736098]

How would I evaluate the indefinite integral [math]int\sin^{n}xdx[/math] ? I tried using integration by parts but I'm still left with an integral.

[Anonymous No.9736099]

>>9736087
https://www.google.com/search?q=integral+power+sine

[Anonymous No.9736108]

>>9736096
Have you tried to express sin^n(x) as a n-sum formula ? I mean you can obtain it by using euler's formula [math] sin^n(x)\,=\, \left( \frac{e^{ix}-e^{-ix}{2i} \right)^n [/math], then Newton's binomia [math] (x+y)^n \,=\, \sum_{k=0}^n Bi(n,k) x^{n-k}y^k[/math] then you rearrange the terms with same exponent to obtain some sum like ...sin(x)+...sin(2x)+...+...sin(nx) and finally integrate ?

[Anonymous No.9736152]

hi, I blocked on something that may be obvious
If I have a frame (x,y,z) and a vector V that is only defined in the plane (y,z) with a 45° angle with the z axis, how can I find its projection on y and z ?
If it was in (x,y) only and 45° with x axis I know that the answer is x = V*cos(45) and y = V*sin(45) but I have no idea for (y,z) and z axis
Any help ?

[Anonymous No.9736160]

>>9735640
Do you have any idea about the research though? Like the one professor I want to ask is doing some wizard shit compared to what Ive learned

[Anonymous No.9736292]

Is the Japanese who wrote this awesome? Or a delusionist?
https://i.imgur.com/EiKnZVi.jpg

[Anonymous No.9736467]

Are p and q identical?
All I get is that they are parallel.

[Anonymous No.9736475]

>>9736467
Also I have 1 more

[Anonymous No.9736504]

>tfw brainlet who never learned stats properly
If I buy three tickets for three separate ten-ticket raffles, how do I compute my odds of winning at least one?
not for homework, I'm actually retarded

[Anonymous No.9736544]

Integral:

[eqn]\int \int y^3 dy dx[/eqn]

Boundaries:

[math]xy = 1[/math]
[math]xy = 3[/math]
[math]y = x^2[/math]
[math]y = 2x^2[/math]

Every time I solve this I get [math]\frac{26}{3}[/math], but the notes say [math]\frac{26}{9}[/math]. Who's right?

[Anonymous No.9736548]

>>9736544
>Every time I solve this I get 263, but the notes say 269. Who's right?
Show your work.

[Anonymous No.9736562]

>>9736504
Easiest way to picture it is to draw a probability tree. You have three separate events, each raffle has two outcomes (win or don't) so you start with one line that splits into 2 for the first raffle, each of these branches split into 2 for the second raffle giving you 4 branches, and they split again for the third raffle giving you 8 outcomes. Add up the probabilities of every branch with at least one win.

[Anonymous No.9736587]

>>9736562
thanks!

[Anonymous No.9736624]

>>9736548
It's 26/9:
[eqn]\int_{\frac{1}{\sqrt[3] 2}}^1 \int_{\frac{1}{x}}^{2x^2} y^3 dy \ dx+\int_1^{\sqrt[3]{\frac{3}{2}}} \int_{x^2}^{2x^2} y^3 dy \ dx+\int_{\sqrt[3]{\frac{3}{2}}}^{\sqrt[3] 3} \int_{x^2}^{\frac{3}{x}} y^3 dy \ dx[/eqn]

[Anonymous No.9736641]

What's the best/safest place to get pirated MATLAB from?

[Anonymous No.9736651]

>>9736641
>safest
new to the internet anon?

[Anonymous No.9736653]

>>9729480
Could we genetically engineer a T shirt Tree

Like a literal tree that grows some wort of t shirts, as cheap clothing

[Anonymous No.9736683]

>>9736504
It’s 1 minus the probability that you don’t win anything. So if the events are independent, and they is a 10% chance to win. Then the odds of winning at least one is 1-(.9*.9*.9)

[Anonymous No.9736754]

is this an ok proof for pic related (just the [math] a [/math] part obviously)
suppose [math] f(a)<\lambda [/math]. then take [math] \epsilon=\lambda-f(a) [/math]. since [math] f [/math] is continuous [math] |f(x)-f(a)|<\lambda-f(a) [/math], whenever [math] |x-a|<\delta [/math] and [math] x\in[a,b] [/math]. but then [math] f(x)<\lambda [/math] whenever [math] x\in[a,b] [/math], which is a contradiction.

[Anonymous No.9736990]

>>9736754
cba reading your proof

if f(a) < lambda, then lambda - epsilon = f(a). By intermediate value theorem, there exists some point a<c<b such that f(c)= lambda. By density of real numbers, there exists a real number d such that a<d<c and again by IVT f(a)<f(d)<f(c), which is a contradiction to your assumption.

[Anonymous No.9737118]

I'm a 3rd year physics student, but I cannot for the life of me finish this extremely simple problem. I tried solving for the time it takes to move from B to C, then I found acceleration by using ∆v/∆t, and I used F_f = ma = µN, but the value I got for µ was incorrect.

[Anonymous No.9737155]

>>9737118
stop posting serway problems it triggers my ptsd

[Anonymous No.9737206]

What would happen to the Japanese dude if this happened for real? As far as how the nuke acts, at least. You may even assume Wolverine can still be Wolverine. But as far as the human, how quickly would he actually die? Instantly upon impact? Could a dude really just hide in a hole or go somewhere underground and just survive a nuke? How long would it take for the heat to dissipate? When he comes back up would he die from radiation 100%? How long would he have to wait?

[Anonymous No.9737219]

>>9729480

I need to become a god in circuits and electronics, any good material,courses,textbooks etc for that?

[Anonymous No.9737255]

I'm taking a course that requires a relatively good knowledge on the basics of organic chemistry, but the highest chem I have is general chemistry 1 from college.
I mostly need to learn how to number carbons in rings, locate reducing ends, shit like that. I think this topic is called stereochemistry but I'm not too sure. Does anyone know what I'm talking about, and are there online resources I can look into?
I'm from a non-STEM degree and just jumped into the science field, so please go easy on me.

[Anonymous No.9737398]

>>9737118
Why don't you just use energy conservation? You have package mass, package velocity, and a total distance over which the force of friction has to act on to remove all the kinetic energy from your package. The coefficient of kinetic friction can be found from the force, gravity and mass.

[Anonymous No.9737401]

>>9737118
For a), a = v^2/2s = 4.8^2/(2*3) = 3.84 => µ = a/g = 3.84/9.81 = 0.391.
For b), potential energy = mgh = 0.2*9.81*1.6 = 3.14J, kinetic energy = (1/2)mv^2 = 0.5*0.2*4.8^2 = 2.3J, loss due to friction = 3.14-2.3 = 0.84J.

[Anonymous No.9737448]

What is the value of z in degrees for this obtuse triangle?
Can I even get it with law of cosines if the given side is adjacent?

[Anonymous No.9737602]

>>9735334
vectors are more interesting desu

[Anonymous No.9737603]

Could someone explain to me how the fuck the kinetic isotope effect works? As far as I understand it's all down to differences in the molecular partition function and zero point energy. But how do you get the weird graphs for ratio of isotope rates vs temperature?

[Anonymous No.9737605]

>>9737219
what level are you?

[Anonymous No.9737607]

>>9737605
>what level are you?
11

[Anonymous No.9737655]

>>9737448
Use both law of cosines and law of sines.

Just write them out using the information you're given.

The rest should follow.

[Anonymous No.9737662]

>>9735334
Just push forward desu.

Your brain will eventually allow you to understand vectors if you give it enough time.

[Anonymous No.9737747]

how can this set have an additive inverse with the operations defined this way? I can show all the other properties of a vector space but not this one.

[Anonymous No.9737771]

>>9737747
If addition is multiplication the additive inverse of x is 1/x

[Anonymous No.9737829]

learning about amu
I know that 1u =1.66 x 10^-24g
but where did 1.66 x 10^-24 come from?

[Anonymous No.9737831]

I understand that it's not true in general for normed vector spaces (in particular for infinitely dimensional ones) that the closed unit ball is not compact, but is the unit sphere compact? That is all the vectors of norm 1.

[Anonymous No.9737862]

Explain poles and zeros to me like I'm a brainlet. Bonus points if you can tie it to actual electrical engineering instead of just spewing mathematical jibberish at me like every other website.

[Anonymous No.9737900]

>>9737829
it's 1/12th the mass of an unbound carbon-12 atom.

[Anonymous No.9737906]

>>9737900
so it's basically 12 divided by 6.02 then divided by 12

[Anonymous No.9737909]

>>9737862
Given a function defined as one polynomial divided by another, points where the numerator is zero are zeroes, points where the denominator is zero are poles.

Except for points which are both a zero and a pole, the function itself will be zero at a zero and infinite at a pole.

In electronics, it mostly applies to transfer functions, i.e. functions which express the ratio of output to input as a function of frequency. A zero of the transfer function corresponds to zero gain (the output will be zero regardless of the input), a pole to infinite gain (which typically means resonance, producing an output without any input).

[Anonymous No.9737913]

>>9737906
It's the reciprocal of the Avogadro constant (the number of C-12 atoms in 12g).

It's roughly equal to the mass of a nucleon (proton or neutron). Except that binding energy also has mass (E=mc^2), so the mass of a nucleon when it's part of an atom isn't the same as when it's on its own.

[Anonymous No.9738103]

having trouble with the algebra here. How do you get the u^2/c^2 =p^2/(p^2+m^2c^2) equation?

[Anonymous No.9738107]

>>9738103
>having trouble with the algebra here. How do you get the u^2/c^2 =p^2/(p^2+m^2c^2) equation?
What have you tried?

[Anonymous No.9738109]

>>9738103
and for the final gamma term. Could someone show me some workings thanks?

[Anonymous No.9738112]

I'm an engineer and I've studied weak formulation and how FEM are supposed to work but I don't think I fully get it yet.

The idea is rather than finding the solution, they find a function that solves for instance for fluids the Navier-Stokes equations?

[Anonymous No.9738177]

>>9736467
>>9736475

[Anonymous No.9738191]

help a brainlet out here
how am I supposed to solve this
am I supposed to just assume they all pass through (0,0)?
or is that irrelevant

[Anonymous No.9738196]

>>9738191
if they're perpendicular the scalar product has to be zero, pretty straight forward brainlet

[Anonymous No.9738197]

>>9738191
If they're perpendicular, their dot product will be equal to 0.

[Anonymous No.9738207]

>>9738196
>>9738197
thanks a ton, dropped out of high school and am currently using 4chin as my personal tutor

[Anonymous No.9738252]

>>9738103
>>9738109

No special tricks, pretty straight forward

[Anonymous No.9738276]

Does anybody know where I can find a table with the conductivity of KCl solutions? I need a few values between 0.1 and 1M

[Anonymous No.9738599]

Why don't electrons spiral into the nucleus?

[Anonymous No.9738635]

Is the force acting on the -3q charge the same on both?
Or am I supposed to calculate the force vectors for the one of the left using cos/sin?

[Anonymous No.9738666]

>>9738276
http://lmgtfy.com/?q=kcl+conductivity+table+type%3Apdf

[Anonymous No.9738696]

>>9738635
Right side is the same as left, if you just rotate your head.
So, they're both same.

[Anonymous No.9738710]

>>9738599
https://www.google.com/search?q=electron+fall+into+nucleus

quantum mechanics laws

[Anonymous No.9738724]

>>9729737
What does "real" mean?

Also, remember that statistics are only useful when talking about populations. They tend to be less than useless in individual cases.

[Anonymous No.9738818]

>>9737255
Organic as a second language
Carey's Organic Chemistry
Master organic chemistry
Khan academy organic chemistry

Do practice problems and use these resources and you should be good to go

[Anonymous No.9738833]

Can someone with a little bit more IQ than I explain to me why if I've a matrix [math]S \in \mathbb{M}_{m \times n} (\mathbb{R})[/math] in row echelon form with r pivots, when I perform a backwards solve from the r-th equation up what comes out happens to be a basis for the kernel? My book instead of telling my why it asks me why.
There's a theorem in the book which tells me that all solutions of the linear system [math]Sx = c[/math] are given by [math]v = v_0 + x_{i_1} w_1 + \dots + x_{i_{n - r}} w_{n - r}[/math], where [math]w_1, \dots, w_{n - r} \in \mathbb{R^n}[/math] not only is a solution for the homogeneous system but also a basis for the kernel and I can't understand how it can tell that all those vectors are linearly independent (about the number of them I'm ok).

[Anonymous No.9738842]

>>9738599
Because they don't spiral at all. They have discrete energy levels. They act more like waves than particles when bound in an atom.

[Anonymous No.9738865]

>>9738599
Electrons within the 1s orbital do have a non zero probability of being found in the nucleus. It is a very small probability. Higher energy electron orbitals are shielded from the full attractive force of the nucleus by lower energy electron clouds blocking them. This makes the probability for higher energy level electrons to be found at the nucelus to decrease to zero.

[Anonymous No.9738910]

>>9738696
>just tilt your head
This is so fucking wrong. Never post here again, The forces have an x and y vector

[Anonymous No.9738926]

>>9738910
Technically you are correct, forces obviously include a magnitude and direction.
What >>9738635 probably asked and >>9738696 probably meant is that the magnitudes of the forces are equal

[Anonymous No.9738935]

>>9738833
> when I perform a backwards solve from the r-th equation up what comes out happens to be a basis for the kernel?
You are just solving a system of equations the same way you did in high school. Multiplying and adding equations to cancel stuff is all that's happening.

>There's a theorem in the book which tells me that all solutions of the linear system...............
If c is in the image of S, then c=Su for some u.
[math]
Sx=c \iff Sx=Su \iff Sx-Su=0 \iff S(x-u)=0 \iff x-u \in \ker{S}=\text{ "linear combinations of the solutions you found (they are solutions as well)" } \iff x=u+\text{ "a linear combination of the solutions" }
[/math]

[Anonymous No.9739027]

How do I prove pic related?

[Anonymous No.9739034]

>>9735020
Alrgiht i'm self-bumping my previous post to cope with the lack of answers.
>No need for topic nor quora edition

[Anonymous No.9739040]

>>9729480

Considering how the earth is rotating, do we experience centripedal acceleration as a result?

[Anonymous No.9739056]

>>9739040
Do you mean a force pushing us outwards?
yes, but considering that at the equator it's about 8.544*10^(-4) m/s^2 you don't really notice it

[Anonymous No.9739057]

>>9739027
you don't

[Anonymous No.9739059]

>>9739027
if simply noting that [math] \displaystyle \sum\limits_{i=0}^n\frac{x^n}{x^i}=\sum\limits_{i=0}^n x^{n-i}[/math] (so the RHS is just the series on the LHS in reverse), then i guess induction

[Anonymous No.9739062]

>>9739059
*doesnt suffice, then...

[Anonymous No.9739098]

Hi, brainlet here (actually the one and only Phenotype)

Why is [math]|\sin(t)|^{-1/p}[/math] of weak [math]L^p(\mathbb{T})[/math]-type? Definition: [eqn]|\{t:|\sin(t)|^{-1/p}\leq \lambda\}|\geq 2\pi -C\lambda^{-1/p}[/eqn] for some [math]C[/math] and all [math]\lambda[/math], or equivalently (the one that I tried to use):
[eqn]|\{t:|\sin(t)|^{-1/p}\geq \lambda\}|\leq C\lambda^{-1/p}[/eqn]
I tried: if [math]|t|\leq \lambda^{-1/p}[/math], then
[eqn]|\sin(t)|^{-1/p}\geq |t|^{-1/p}\geq \lambda[/eqn]But this only shows that [math]|\{t:|t|^{-1/p}\geq \lambda\}|\leq |\{t:|\sin(t)|^{-1/p}\geq \lambda\}|\leq C\lambda^{-1/p}[/math].
I also tried [math]\frac{2}{\pi}|t|\leq |\sin(t)|[/math], bu this only holds for [math]|t|\leq \frac{\pi}{2}[/math], so I cannot prove anything for the other [math]t[/math].

Help me out pls. Thanks

[Anonymous No.9739122]

>>9739098
Correction:

[math]|\{t:|t|^{-1/p}\geq \lambda\}|\leq |\{t:|\sin(t)|^{-1/p}\geq \lambda\}|[/math] instead of [math]|\{t:|t|^{-1/p}\geq \lambda\}|\leq |\{t:|\sin(t)|^{-1/p}\geq \lambda\}|\leq C\lambda^{-1/p}[/math]

[Anonymous No.9739137]

>>9739098
Correction:

"if [math]|t|\leq \lambda^{-p}[/math]" instead of "if [math]|t|\leq \lambda^{-1/p}[/math]"

[Anonymous No.9739174]

>>9739059
thank you
>in reverse
fuck. How can I simplify pic related then. Is there a way to "reverse" what I have inside of the braces so I can use x^i instead of the fraction?

[Anonymous No.9739175]

can someone help me with this?

I know I have to check if

L(ax)=aL(x)
L(x+y)=L(x)+L(y)

[Anonymous No.9739184]

>>9739175
Hi, Phenotype here, not gonna use [math]\LaTeX[/math], but

f(a(x,y,z))=f(ax,ay,az)=(az,ax,ay)=a(z,x,y)=af(x,y,z)

Other one is analogous: use vectors (x1,y1,z1) and (x2,y2,z2).

[Anonymous No.9739185]

>>9736160
I've been working on research with my program advisor and another undergrad. I knew that my classmate was working with him so I just kept pestering my professor about it until I got in on it. I've been trying to learn as much theory as I can, but this is advanced stuff that takes years to learn. But our part in the research is just codemonkey stuff, so we don't need some deep understanding of the mathematics. It has to do with modular forms though which I find really fascinating and try to learn as much as I can about.

[Anonymous No.9739197]

[math]
\frac{e^{-5s}*(2s+3)}{s(s^{2} + 2s + 5)}
[/math]

Please tell me how I can split this into partial fraction such that I can easily take a piecewise inverse laplace

Brain is failing me

[Anonymous No.9739203]

>>9739197
note that the * in the top term is multiplication, not convolution

[Anonymous No.9739249]

>>9739197
Hi, Phenotype here.
I'll give you heuristics:
first ignore the multiplication with e, because that's an easy inverse that you can do afterwards.
try partial fraction with s and (s+1)^2+4 in their denominator. The first one is easy and the other will be cos or sin. Now use the inverse with e trick.

[Anonymous No.9739366]

I'm a mechanical engineer, and I want to learn more about electromechanical devices and the principals behind them like acutators, dc motors... etc. Would you anons please recommend me textbooks or resources on this subject?

[Anonymous No.9739402]

in the proof of "contour independence" why can we suppose [math] \Gamma_2 [/math] lies within the other contour? how are cases like at the bottom of pic related covered?

[Anonymous No.9739694]

Will I go into ketosis faster if I just dont eat, or will having 10/20g of carbs a day induce it in the same timespan anyways

[Anonymous No.9739797]

How can I calculate this sum?
[math]\sum_{k=1}^n kln(1 + \frac{1}{k})[/math]

[Anonymous No.9739805]

>>9739797
ln(a)+ln(b) = ln(ab)

[Anonymous No.9739838]

Suicide by caffeine overdose, is it posible? What is the mechanism of death?

[Anonymous No.9739845]

>>9739366
The MIT class on electromechanical shit. You can download all the lectures and quizzes

[Anonymous No.9739848]

>>9739402
Pick a circle small enough that it is inside the interiors of [math]\Gamma_1[/math] and [math]\Gamma_2[/math]. The integral on this circle is equal to both integrals by what you posted.

[Anonymous No.9739898]

>>9739797
k can be put into the argument of the natural log and thus you have the natural log of exp(n) therefore, you just have n and can take n as it approaches infinity to show that it diverges. or You could show that the sum of k to n, if n is an element of the integers, is n(n+1)/2. I don't really know what you want to do past that but here we are.

[Anonymous No.9740199]

>>9737831
I'm pretty sure the very same counter example works, take the space of bounded sequences and take as a sequence the elements which have all zeros save for its ith term. This sequence won't have a convergent subsequence

[Anonymous No.9740442]

I feel like I'm having a lot of difficulty understanding basic electricity, like voltage and current. Like are electrons a physical thing being created/lost or what? Is it basically that current is the number of electrons and voltage is how strongly they flow? Any recommended reading/video that will explain it to me like I'm retarded?

[Anonymous No.9740452]

>>9740442
Actually my major source of confusion is that voltage is defined as the 'potential difference'. What does that actually mean? How do you set that?

[Anonymous No.9740466]

>>9733516
>I posted it again look look looooooooook!!!!

[Anonymous No.9740468]

>>9740452
usually a lack of charge is the potential difference. they'll move towards higher potential. you can set it by just removing electrons or siphoning them somewhere else (why a ground works)

[Anonymous No.9740475]

>>9740468
Could you give me an example of moving from a low potential to a high potential?

[Anonymous No.9740584]

>>9739848
Not the one who asked the question, but...
Wow, that was simple. I drawed all kinds of stuff and tried to apply mental gymnastics, but nothing worked. It's just applying the conclusion twice. Thanks.

[Anonymous No.9740654]

why astranats do this?

[Anonymous No.9740668]

I have a question about the sun height/angle. So on summer solstice the sun is highest/in zenith. So when it is summer solstice does this mean that the sun is about as high in southern sweden as it is in bali,indonesia?

[Anonymous No.9740677]

Hey bros,
Having a little bit of trouble working out whether this stunt is actually realistic - what am I meant to do/calculate?

[Anonymous No.9740686]

looking at a rate equation of:

Rate = k[H2] [NO]3

can i say that it is a first order reaction with respect to hydrogen, a second order reaction with respect to nitric oxide, and it is a third order reaction overall?

or is it a fourth order reaction because the sum of all individual orders is 4? the text i'm learning from is not very clear

[Anonymous No.9740688]

>>9740677
I'd try the looking at the force with which the man would enter the pool.

[Anonymous No.9740696]

Can someone explain me the "engineer are gay" meme and the general hate

[Anonymous No.9740703]

>>9729989
a heart would be 1/4

[Anonymous No.9740862]

>>9729480
https://www.scientificamerican.com/article/strange-but-true-infinity-comes-in-different-sizes/

[Anonymous No.9740908]

>>9740686
Which reaction should be?

[Anonymous No.9740986]

can I believe in quantum immortality and biocentrism without believing in out of body experiences?

[Anonymous No.9740985]

>>9729737
Yes, but few people even know what it represents. It's real and it matters immensely

[Anonymous No.9740994]

>>9730183
can you simplify the answer at all? (too lazy to check myself)

[Anonymous No.9741072]

>>9739175
clear

[Anonymous No.9741075]

Is there a service like myheritage, 23andme, etc, which gives you medical results instead of or together with "muh ethnicity"?

Couldn't really give two shit about race, I just want to know if I'm predisposed to something or not.

[Anonymous No.9741078]

>>9739402
key point is "simply connected". you can shrink one of them to the point z_0 smoothly and since gamma _1 doesn't go through the point z_0, then by the topology of the complex numbers, there is some "space" between gamma_1 and z_0 through which you can squeeze gamma_2.

[Anonymous No.9741086]

>>9740654
it's hard to imitate zero gravity. there is a system of strings that suspend them so that they appear to float. for practical purposes, many are located close to the arms, but this puts a certain amount of force on them. in order to take the photos, they need to hold tight, and the easiest way to look natural and be tight is to hold your arms together

[Anonymous No.9741095]

>>9741086
Thank you, hopefully NASA get the budget to upgrade their harnesses, go NASA!

[Anonymous No.9741104]

>>9741086
>a flat earth post

[Anonymous No.9741136]

>>9729480
let's say I am given a certain velocity-position function, how do I find the adequate velocity-time function?
for example:
V(x)=x^2
V(t)=?

[Anonymous No.9741163]

HOW THE FUCK DO I FIX THIS!!!!!

MY PROFESSOR IS GOING TO BE HERE TOMORROW TO CHECK ON MY PROGRESS AND IF HE SEES THIS HE'S GOING TO FLIP THE FUCK OUT AT ME

[Anonymous No.9741167]

>>9741136
>>9741136
Parametrize the equation, multivariable calc stuff

[Anonymous No.9741170]

>>9741075
They do that yes, but they will then sell your information to insurance companies who will alter your monthly payments based on your risk for genetic diseases.

[Anonymous No.9741179]

>>9741136
You need to know what x(t) is and plug that in v(x) to get v(t)

[Anonymous No.9741182]

>>9740686
Fourth order

[Anonymous No.9741183]

Is this value for the Bohr Radius correct? It seems to be missing e0 and a pi in the denominator

[Anonymous No.9741208]

>>9741136
t.

Phone fag

[Anonymous No.9741223]

>>9741170
Thank the gods I don't live in a third world country like the US and have Universal Healthcare.

[Anonymous No.9741255]

>>9741183
Your book gave the radius in Guassian units, which cancels outs the 4pie0 term

[Anonymous No.9741260]

>>9741136
You and people that replied to youare niggers.
First you have v=x^2 and v=dx/dt
Combining this tou get dx/dt=x^2
dx/x^2=dt. Noe solve this diff equation and plug x(t) into v(x) and its done

[Anonymous No.9741276]

>>9739175
You can represent f as a matrix and show this trivialy

[Anonymous No.9741512]

I don't understand how:
(1/n) ((1-(e^(1/n)^n))/(1-e^(1/n)) = ((1/n)/(e^(1/n)-1))

Someone can help me please?

[Anonymous No.9741515]

>>9741512
>(1/n) ((1-(e^(1/n)^n))/(1-e^(1/n)) = ((1/n)/(e^(1/n)-1)) * (e - 1)

sorry

[Anonymous No.9741516]

In a crossed magnetic and electrical field, is the motion of a charged particle a spiral?
I want to say it is, but I vaguely remember hearing during lecture a different shape.

[Anonymous No.9741518]

>>9741512
simple, it is wrong

[Anonymous No.9741534]

>>9741518
https://youtu.be/qXDhD4y_GtQ?t=2m50s

Have I made a mistake in recopying?

[Anonymous No.9741538]

are electrons just really small planets, and atoms just really small solar systems?

saging my own post

[Anonymous No.9741560]

>>9741518
I've just tested with a calculator and it's good man, with n = 7 it makes 1.598468667

[Anonymous No.9741572]

>>9741538
I was actually just thinking about this.
The earth is in orbit with the sun and also spins. Similarly, the electron is in orbit with the nucleus and has it's own spin.

[Anonymous No.9741575]

>>9741512
oh right i didnt see the m in the exponent >>9741518
just notice that (e^1/m)^m = e^1

[Anonymous No.9741576]

Why did Maxwell invent displacement current for Ampere's law? I can't find an answer online. Why was it necessary to complete Ampere's law?

[Anonymous No.9741585]

>>9741576
didnt take into account the current between capacitor plates

[Anonymous No.9741593]

>>9741585
Ah, so displacement current is basically the current between the plates

[Anonymous No.9741611]

>>9741593
essentially

[Anonymous No.9741613]

>>9741575
thanks but sorry, even in noticing that, I don't see how continue
I'm blocked here: (1-e) / (n - n * e(1/n))

[Anonymous No.9741628]

>>9741613
Why are you doing things that use the letter e when you dont know basic fucking algebra?

[Anonymous No.9741632]

>>9741613
>>9741628
ok nice and slowly so brainlet here can understand
[eqn]\frac1 m \frac{1-(e^{1/m})^m}{1-e^{1/m}}= \frac1 m \frac{1-e^{m/m}}{1-e^{1/m}}= \frac1 m \frac{1-e}{1-e^{1/m}}= \frac1 m \frac{-(e-1)}{-(e^{1/m}-1)} =\frac1 m \frac{(e-1)}{(e^{1/m}-1)} = \frac1 m \frac{1}{(e^{1/m}-1)}(e-1) = \frac{\frac1 m }{(e^{1/m}-1)}(e-1)
[/eqn]

[Anonymous No.9741634]

>>9741628
The letter e = exponential function you know?

[Anonymous No.9741639]

>>9741632
oh ok, multiply by -1 / -1 was the thing, thx

[Anonymous No.9741640]

>>9741634
>The letter e = exponential function you know?
yes i fucking know e is the fucking exponential function, but it just so fucking happens that you dont know enough fucking algebra to be at the level to define this function through calculus

i would suggest either start again with the basics, or a bullet to the head

[Anonymous No.9741643]

>>9741640
I don't need to know the definition of that function for now.

[Anonymous No.9741645]

>>9741643
>us education system

[Anonymous No.9741651]

How difficult is Calc 3?
I’ll be taking it Fall ‘18 and the last time I took Calc 2 was Spring ‘17.
My recent math courses were differentials Fall ‘17 and Phys Electricity/Magnetism this semester.

[Anonymous No.9741670]

>>9741651
easy. That's vector calculus, with a touch of partial derivatives and multiple integrals. However, it is an important class so don't try and skate through it. So much of it will remain pertinent throughout your stem education.

[Anonymous No.9741679]

>>9741651
>>9741670
A question for (one or both of) you:
How do/should you know what calc 3 is about? Does every university in US have the same courses or course names? Is the calc 3 course everywhere the same in US, and also the same for physics and other studies?
t. non US citizen

[Anonymous No.9741686]

>>9741651
It's extremely easy and intuitive IF you know Linear Algebra well and if you start treating the "dx"s unrigorously (purely intuitively: infinitesimal volume, infinitesimal area, etc).

[Anonymous No.9741692]

What would be necessary to eliminate the need to poop for humans? I understand we do it to like detoxify the body of wastes such as dead cells and etc beyond food. But I simply want to know, theoretically, how could a being not have to shit?

[Anonymous No.9741698]

>>9741692
You partially answered the question.

[Anonymous No.9741702]

>>9741698
well i am in this thread for a reason

So then we'd just have to be capable of either 1.) not producing said wastes or 2.) be capable of burning up said wastes in some manner?

Could this even be done through artificial means? Hypothetically

[Anonymous No.9741717]

>>9741702
You’d have to totally redesign the body. The digestive system and everything tied into it (every other system basically) would need to be totally different. Can you think of any mammal that doesn’t shit?

[Anonymous No.9741730]

>>9741679
This is a question for anyone who knows why btw.

[Anonymous No.9741743]

>>9741679
>>9741730
I think Calc I, II, and III cover pretty much the same material at most state schools and community colleges in the US. Special snowflake schools and top tier universities can be different though. My Cal III class was pretty much as >>9741670 described. And yes, the same seems to apply to physics as well.

[Anonymous No.9741761]

I know the answer is C
I know the top triangle is a similar triangle to the whole triangle. But I am an absolute brainlet and I'm not sure how to generate the equation

[Anonymous No.9741785]

>>9741761
Use Pythagoras on AB and AC to find BC=8.
Observe that Area big triangle = Area small triangle + small rectangle + small triangle to find 24=(8-y)x/2+(8-y)(6-x)+(6-x)y/2.

Indeed C.

[Anonymous No.9741818]

>>9741702
> be capable of burning up said wastes in some manner?
This.

Bear in mind that cellulose is highly indigestible. Even herbivores only manage to partially digest it.

[Anonymous No.9741869]

>>9741785
Ah, I have to do it based off of area. Thank you

24=(8-y)(x/2)+(8-y)(6-x)+(6-x)(y/2)
24=8x/2-xy/2+48-6y-8x+xy+6y/2-xy/2
48=8x-16x-xy-xy+2xy-12y+6y+96
-48=-8x-6y
24=4x+3y
24-4x=3y
8-4x/3=y

[Anonymous No.9741875]

>>9740654
Probably to keep their arms from floating up.

[Anonymous No.9742291]

>>9741572
Too bad electrons don't really orbit nor spin.

[Anonymous No.9742340]

Hey medfags, can someone help me with this problem? I am going out of town on the 16th and my next refill for Adderall is due on the 16th. I have been on a steady dose for 10 months and have never asked for an early refill. will the doctors be upset or suspect me of abuse if I ask for my refill 1 day early? I live in Texas if that matters for the relevant laws.

[Anonymous No.9742828]

Does field of view follow an inverse square law?

[Anonymous No.9742892]

I dont understand how to prove formulas by induction. Help

[Anonymous No.9743030]

>>9742892
prove the base case, assume it is true for every number up to n, then prove it true for n+1 based on the assumption that it is true for numbers up to n

[Anonymous No.9743061]

How would I find out how much weight a grade has towards a total % for it?
e.g. getting 100% in a test counts towards 5% of the overall grade.
If 80% was achieved in that test, how would that translate relative to the 5% overall?

[Anonymous No.9743106]

Basic terminology here.

What's the most concise way to say
"X changes n amount per T"? It's delta right?
Delta X = n (T is assumed to be 1)
Or is that inappropriate terminology?

Also what about multipliers or fibbinochi stuff?
Like how do might I say:
X multiplies by N every T
Or
X increases/decreases by a fibbonichi number... Uh I don't know how to work it but I think you understand.

I can google if someone points me in the right direction. Not a math guy.