/sci/ - Science & Math

no, retard

>>12022671
>>12028860
>>12028881
God I fucking hate Thought Emporium. Only visit his videos when you have to. Motherfucker has a superiority complex when you're talking to him in private, and god help you if you/he brings up politics.

Biohacking is fun thought.

>>12032464
I M A G I N E

For an EM wave in a vacuum that has a moving envelope, is [math]c[/math] the phase velocity or the group velocity?
>>12032464
No. You add [math]\frac{1}{k}[/math] for all of [math]\left{k, k+1, ... , 2k-2, 2k-1 \right}[/math]

The dimensional analysis of Force is [math]M \frac{L}{T^2}[/math] ?

college freshman here, so my situation is
>get credit for calculus 1 and 2 through AP exams
>try to schedule matrices this semester, system doesn't let me
>Find out from the registrar that it's university policy that you can't use AP credit to fulfill prerequisite requirements for other courses, so I'd have to take calc 1 and 2 anyway
Do most universities do this bullshit or is mine being especially bad?

My mom's boyfriend directed me here because you're all so friendly to newbies.

I recently moved into a new location in which I do not pay for electricity or internet so I wanted to dip my toes into mining. I'm currently managing a whopping 1.8 MH/s on my Lenovo Thinkpad 5... I'm guessing this is about as good as a laptop can get?

If I wanted to buy an actual rig for Ethereum mining is there any generally accepted "correct" choice? Is it worth taking out a (zero interestl) loan to take advantage of this unique opportunity of not having to pay for electricity? Do I need to know how to overclock? Is it difficult to learn?

Thanks guys

>>12032812
phase
>>12033072
yes

I have three weeks before the beginning of the coming fall semester. What should I study? Perhaps I could go balls deep into abstract algebra or finally make the leap into physics. Any other recommendations?

any good book on waves from the classical perspective?
i fucked up and never understood waves well in hs and now i am deep into it while not understanding anything. i need something that builds from 0 knowledge, is straight to the point and mostly focuses on the mechanical and math perspective of waves both the longitude and the transversal ones

Still working on getting an agreeable answer here that I understand. My work thus far is
[math] \int_{\frac{\pi}{6}}^{\frac{\pi}{3}}\int_0^{\frac{\pi}{4}}
2sin(\phi)cos(\theta) + 2sin(\phi)sin(\theta) + 2cos(\phi) [4sin(\phi)]d\theta d\phi
[/math]

Does that look right? As long is the integration is set up correctly I can handle the remainder ezpz. One of the anons who helped me in the last thread said the [math]p=2 \rightarrow p^2 = 4[/math], so that's why I have 4 in the square brackets, but I was wondering how p was determined so easily, is it as easy as just finding the max value out of the <i,j,k> components in my function? Probably, just wondering though. I feel somewhat confident in the form of this answer so I'm gonna proceed but lmk if it looks wrong pls

>>12033185
What classes are you taking in fall? Personally I'd either take the time off and do something completely unrelated, but perhaps sparsely view some motivational material so you enter the course with piqued interest.

>>12033231
Linear and nonlinear waves by whitham
>>12033314
Did you just add the components? In that case it's wrong.
Differentiate r with respect to phi and theta.
Then take the cross product of both derivatives and integrate over the surface. Because the surface is in spherical coordinates you have to include the determinant of the metric tensor. That's why it's r^2*sin phi. Your surface is a sphere with radius 2, so r=2 and r^2=4

>>12033355
>Because the surface is in spherical coordinates you have to include the determinant of the metric tensor. That's why it's r^2*sin phi. Your surface is a sphere with radius 2, so r=2 and r^2=4
Actually, scratch that. You don't need that term

>>12033332
Cybersecurity, topology, a business foundations course, and math capstone. I've pretty much completed all the requirements for my math/CS double major but still feel somewhat lacking in my abilities. Furthest it ever got at my university was abstract algebra and real analysis, both of which were pretty simplified in retrospect (abstract algebra prof used Pinter's text and real analysis prof used one he wrote himself). I'd like to feel confident enough for the GRE math subject test at the very least, but it's mostly for the sake of keeping my brain active.

>>12033314
>ezpz
on second thought can someone spoonfeed me how to solve the first integral? It would just be like this right
[math]\int_0^{\frac{\pi}{4}} 8sin(\phi)(sin(\phi)cos(\theta) + sin(\phi)sin(\theta) + cos(\phi)) =8sin(\phi) \int_0^{\frac{\pi}{4}} (sin(\phi)cos(\theta) + sin(\phi)sin(\theta) + cos(\phi)) \\
= 8sin(\phi) \int_0^{\frac{\pi}{4}} (sin(\phi)(cos(\theta) + sin(\theta)) + cos(\phi)) \\
= 8sin(\phi)(sin(\phi) \int_0^{\frac{\pi}{4}} (cos(\theta) + sin(\theta)) + cos(\phi))[/math]

were those operations all legal?

>>12033393
Nice, I'm also doing math/cs double. I'd try to find some cool mathy model thing you can put together and show off, in that case.

>>12033355
>Did you just add the components? In that case it's wrong.
yes I did, I thought that was the vector equation..

>Differentiate r with respect to phi and theta.
[math]
r_{\theta} = <-2sin(\phi)sin(\theta), 2sin(\phi)cos(\theta), 0> \\
r_{\phi} = <-2cos(\phi)cos(\theta), -2cos(\phi)sin(\theta), -2sin(\phi)> \\
[/math]
>then take the cross product
[math]
|r_{\theta} \times r_{\phi}| = <-2sin(\phi)cos(theta)(-2sin(\phi)) - 0, -(-2sin(\phi)sin(\theta)(-2sin(\phi)) - 0), -2sin(\phi)sin(\theta)(-2cos(\phi)sin(\theta)) - 2sin(\phi)cos(\theta)(2cos(\phi)cos(\theta))
[/math]

And then I integrate over that monster?

>>12033442
>>12033376
>>12033355
>you don't need that term
why not?

And also, if I don't just add the components to form the vector equation that I need to integrate over, what do I do? I have the cross product result above, but what am I actually integrating on?

Thanks for all the help btw

Explain the dot product to me like I'm two years old.

>>12033453
Suppose you have Milk = <goo, goo> and Bottle = <ga, ga>. Then Milk . Bottle = googa + googa.

>>12033453
you need to multiply two vectors together. however, vectors aren't just a single number, they have multiple dimensions.
how can you multiply two vectors in a way that produces a meaningful result? there are a couple useful ways. the dot product returns a single number which I like to interpret as "the total magnitude of the vectors that point along the same dimensions"

>>12033451
you're just asking for the process, it seems that you don't know the logic behind it very well (not trying to be rude).
I really recommend reading a textbook to explain this topic, otherwise you'll know how to apply it to this specific problem but that's it.

personally I forgot how to do this shit a long time ago but I know your current line of thinking isn't correct. You can't be integrating over a vector, it has to be a scalar function, so I know it's wrong for that reason at least.

>>12033314
[eqn]
\partial_\phi r = 2(\cos\phi\cos\theta,\cos\phi\sin\theta,-\sin\phi)\\
\partial_\theta r = 2(-\sin\phi\sin\theta,\sin\phi\cos\theta,0)\\
\partial_\phi r \times \partial_\theta r = 4(\sin^2\phi\cos\theta, -\sin^2\phi\sin\theta, \cos\phi\sin\phi\cos^2\theta+\sin\phi\cos\phi\sin^2\theta)\\
|\partial_\phi r \times \partial_\theta r | = \sqrt{\sin^4\phi+\sin^2\phi\cos^2\phi}=4\sqrt{\sin^2\phi}=4\sin\phi \\
[/eqn]
The term I mentioned is the thing you calculate apparently, so you don't need that.

Why is anime posting anon so smart? He literally knows every fucking topic.

cos is x (run) moving from right to left. Sin is y (rise) moving from 0, upwards and then downwards. And tan is the tangent. All changing geometric lines.
Do I understand that right?
However what's happening when people say the tangent is dy/dx and the slope is also dy/dx?
Is it the same notation for change and a very small part of, the slope is a different thing from the tangent right?

>>12033529
Tangent as in [math]tan (x)[/math] and tangent line to the function are two different things.

>>12032464
Can anyone point me to a characterization of epimorphisms in the category of normal topological spaces?

I was hinted to use Urysohn's lemma. but all i can think of is that the forgetfull functor from Top to Set is faithfull and hence reflects epimorphisms so that epimorphisms are precisely surjective.

>>12033512
>He literally knows every fucking topic.
just math and physics. also he probably learned how to put his autism into good use and his insatiable attention deficit brain can't go a day without learning something new.

>>12033512
because he watches anime

>>12033553
so dy/dx and dy/dx can mean totally different things. I don't really get what's happening. It's just where the hypotenuse is pointing in regards to the rise at the right side? And then it becomes undefined when the slope is vertical because it's infinite?

>>12033621
like yeah, I get it's sinx/cosx and becomes undefined because you're dividing by 0 at one point but what on earth is it. sin is y, cos is x. tan is?

>>12033643

>>12033643
Just think of trigonometric functions as ratios of sides of right triangles for a given angle.

>>12033570
>epimorphisms are precisely surjective.
This is false. The inclusion of Q into R is a nonsurjective epimorphism in your category.

>>12033652
So. We imagine a vertical line at x = 1. tan(x) is finding the y point where the hypotenuse hits the vertical line? Is that right?

>>12033677
youŕe wrong.

given an epimorphism f : X --> Y,
let g = indicator function f(X) so g : Y --> {0,1}
and h = constant 1, so h : Y --> {0,1}
and equip {0,1} with the discrete topology, then we see that gf = hf. and since f is epi we have g = h meaning f is surjective.

>>12033677
it means your map is not an epimorphism.

>>12033672
He’s asking for a geometric interpretation of the magnitude of the tangent function. You’re essentially restating the problem by its definition with an algebraic formulation of the geometry. This doesn’t teach him anything and provides no insight.

>>12033724
>gf = hf

>>12033687
In this specific example, yes.

>>12033736
ah sorry for being rude

>>12032464
Hey guys! Does any of you know about teaching? My question is how to you get a student who always answers all questions with "I don't know" to actually start thinking? He seems to care too much to answer correctly (even when he isn't expected to know the answer) and so he is afraid to be wrong which leads him to avoid thinking. I think a faggot elemntary school math teacher who always told children they are wrong because of his supperirity complex fucked him up. Any help is appreciated.

How accurate is this

[math]S_c(y)=\sup\{y^Tx|x\in C\}[/math]

Show that

[math]S_{A+B}=S_A+S_B[/math]

We first show [math]S_{A+B}\subseteq S_A+S_B[/math]
let [math]x_1\in A,x_2\in B[/math] then [math]x=x_1+x_2\in A+B[/math] and
[math]S_{A+B}=\sup\{y^T(x_1+x_2)|x_1+x_2\in A+B\}[/math]
Since [math]\sup\{y^Tx_1|x_1\in A\}\in S_A[/math] and
[math]\sup\{y^Tx_2|x_2\in B\}\in S_B[/math] then
[math]\sup\{y^Tx_1+y^Tx_2|x_1\in A,x_2\in B\}\subseteq\sup\{y^Tx_1|x_1\in A\}\sup\{y^Tx_2|x_2\in B\}[/math]
I'm having a hard time establishing what it means to be in the set S

How accurate is this

[math]S_c(y)=\sup\{y^Tx|x\in C\}[/math]

Show that

[math]S_{A+B}=S_A+S_B[/math]

We first show [math]S_{A+B}\subseteq S_A+S_B[/math]
let [math]x_1\in A,x_2\in B[/math] then [math]x=x_1+x_2\in A+B[/math] and
[math]S_{A+B}=\sup\{y^T(x_1+x_2)|x_1+x_2\in A+B\}[/math]
Since [math]\sup\{y^Tx_1|x_1\in A\}\in S_A[/math] and
[math]\sup\{y^Tx_2|x_2\in B\}\in S_B[/math] then
[math]\sup\{y^Tx_1+y^Tx_2|x_1\in A,x_2\in B\}\subseteq\sup\{y^Tx_1|x_1\in A\}+\sup\{y^Tx_2|x_2\in B\}[/math]
I'm having a hard time establishing what it means to be in the set S

please?? quick!~

>>12033840
Final Exam right? Recall that the gradient vector(s) are orthogonal to the level sets of a function. Remember also the definition of the tangent plane. You have all the information needed. Good luck and remember that you only cheat your future self by failing to put in the necessary effort before your lack of knowledge is exposed!

>>12033840
Calculate df

>>12033846
>>12033862
I got too paranoid and deleted, I accidentally started my exam thnking it was the practice final LMAO. I didn't even realize I was doing the final until like 30 minutes in..

Anyway, if the eqn is [math] 2x^2-3y^2+z^2 = 8 [/math], then by finding all three partials and plugging in values for our point (1,1,3) we have vector <4,-6,6>, right? now I just have to remember tangent plane stuff

>>12033867
If you understand what the total differential of a function at a point is and what the gradient vector (singular) is for this level set and the specified point you're off to a good start. The only other advice I can give you is that the tangent plane, the point of evaluation and the gradient are intimately connected and if you think very hard you'll have the answer in no time at all.

How so I create a new material, like plastic? I already have a base material I want to use. Are there any books on this process?

>>12033880
tangent plane is just 4(x-1) - 6(y-1) + 6(z-3) = 0, correct?

>>12033118
>mom's boyfriend
cringe
>mining in 2020
double cringe
Mining is not economically viable. If you live with your mom and her boyfriend, they will have unholy energy bills each month and ask you to stop mining. Suggest you buy an FPGA instead of a bunch of graphics cards if you want to mine for the sake of learning, and overclock your normal PC if you want to learn about that.
>>12033231
MIT OCW Physics III
>>12033453
Dot product is the amount by which two vectors coincide multiplied by magnitudes. Parallel vectors have the maximum dot product. Perpendicular have zero. Antiparallel have minimum.
Imagine you were pushing a cart forward on a track. When you push parallel to the direction of the track, you do the most effective work. When you push perpendicular to the track, you're not doing any work. When you push backward along the track, you're undoing the work you did before.
>>12033882
You want to create a new kind of plastic? Looks like you'll need to learn organic synthesis, polymer chemistry, and material science.

>>12033913
>organic synthesis, polymer chemistry, and material science.
Thanks, I'll look into it

>>12033471
>>12033913
Regarding dot product, I'm trying to see how the little dot product formula is derived from the law of cosines but I get stuck. Suppose you were to interpret a couple vectors (a) and (b) and their displacement vector (is that the term? Just the one connecting their terminal ends), let's call it (c). Looking at it like a regular triangle, the law of cosines is c^2 = a^2 + b^2 -2abcos(theta). Doing some algebra results in 0.5(a^2 + b^2- c^2) = abcos(theta). That would mean that a•b in vector terms should be equal to 0.5(||a||^2 + ||b||^2 - ||c||^2). This is where I get lost. I don't see or can't discern the connection.

>>12033987
||c||^2 = <c,c> = <a-b,a-b> = <a,a>+<b,b>-<a,b>-<b,a> = a^2+b^2-ab cos theta
Also you can think of the projection of a onto b and scaling the result by b

>>12033724
Indicator function isn't necessarily continuous

How could i represent a vector ([math]\vec{v}[/math]) with unitary vectors ( [math]\hat{j} = x, \hat{i} = y[/math] ) in a cartesian plane if the vector has the direction South-East? the module of [math]\vec{v}[/math] is [math]500m[/math]

should i do [math]700 \hat{i} \hat{j}[/math] ?

>>12034337
i fucked up, [math]\hat{i} = x, \hat{j} = y[/math], this is the one

>>12034337
i fucked up again module of [math]\vec{v}[/math] is [math]700m[/math] jesus fucking christ

>>12033570
I M A G I N E

I know that when in 1D, the wave function, when squared, is the derivative of probability in function of X, so integrating it across all space gives me 1. Now, when working in 3D, does it remain the derivative in function of a length (in this case, radius), or in function of space? Aka, when integrating the squared function, should I add a dV or a dr to the integral?

>>12033987
First, consider the case where both vectors lie in the X-Y plane. You have two vectors:
v1 = [r1*cos(a1), r1*sin(a1), 0, 0]
v2 = [r2*cos(a2), r2*sin(a2), 0, 0]
Their dot product is
v1·v2 = r1*cos(a1)*r2*cos(a2) + r1*sin(a1)*r2*sin(a2)
= r1*r2*(cos(a1)*cos(a2) + sin(a1)*sin(a2))
= (r1*r2)*cos(a1-a2)
IOW, the dot product of two vectors is equal to the product of their magnitudes times the cosine of the angle between them.

Second, note that the dot product is invariant under rotation. The dot product is just transposition and matrix multiplication: a·b = a^T b. So:
(M a)·(M b)
= (M a)^T (M b)
= (a^T M^T) (M b)
= a^T (M^T M) b
= a^T (M^-1 M) b [*]
= a^T b

[*] For an orthonormal matrix (i.e. a rotation), the inverse is equal to the transpose.

So given 2 vectors in R^n, you can rotate them (without changing their dot product) so that only the first two components are non-zero (i.e. to the X-Y plane) then use the formula for the 2D case.

>>12034453
you need to integrate over the volume element dV

>>12034337
the directions add as squares. so [math]\sqrt{v_{south}^2+v_{east}^2}=700[/math]
if it's exactly southeast you can solve this equation easily

>>12034643
>>12034344
>>12034337
it it wasn't clear enough the answer would just be
[math]v=\frac{700}{\sqrt{2}}\hat{i}-\frac{700}{\sqrt{2}}\hat{j}[/math]

Whats the physics inside an o neil cylinder?

>>12034667
are you familiar with uniform circular motion?

>>12032464
I current do machine learning for a business, for not alot of $$$.

I would love to do something less tedious and better paid at a tech company instead.

I was thinking about doing some sort of AWS certification.

Is this a good idea or is AWS cert a meme?

>>12034671
Yes but what happens when i take off in a plane? Does gravity linearly decrease to 0 in the middle of the cylinder?

>>12034115
it is with the indiscrete topology. mybad.

Scientifically speaking, is there any greater suffering than when you're sitting with your legs crossed in a chair like an autist and they go numb and then the only way to get the blood flowing again is to be forced to stand?

>>12035896
i felt this

why is the tangent in the third quadrant positive, I mean the geometric line is still on the negative side right. Or is it because it's pointing up? Or something like that.
Or is it just simply because you're dividing two negatives (obviously)?

are there any irrational numbers [math]a, b[/math] such that [math]a \neq b[/math], [math]a[/math] and [math]b[/math] cannot be expressed as [math]c\sqrt{d}[/math] and [math]e\sqrt{d}[/math] (they have no "rooty common factors", so to speak), and [math]ab[/math] is a rational number? this might be a dumb question but i thought about it for a while and cant think of any examples

>>12032812
In vacuum it is both, vacuum is nondispersive so the phase and group velocities are both c and the moving envelope moves at the same speed as the moving phases of the wave. Keep in mind Einstein's relation, vp vg = c^2.

>>12033314
you're being told it's a part of a sphere with radius 2. you can ignore the position vector you're being given here and just integrate r*sin(theta) dtheta dphi along your provided limits, given r = 2.

How do you find C with indefinite integrals? Is it possible?

>>12036051
To fully constrain an antiderivative (indefinite integral) you need two pieces of information. The integral equation is one, and a known value of the antiderivative (initial value, boundary value, even just as the function tends towards at infinity can do it sometimes) is usually the second.

>>12036051
not unless youre given some initial condition, like for example, if youre given the velocity function for a particle and youre also told that the particles position at t=0 is 8 (or whatever), then you can solve for C in the particles position function

>>12035959
Do you mean here? >>12033652
You're looking for the intersection at [math]x = 1[/math], it's positive.

Why do I find it so difficult to understand programming articles and tutorials beyond the basic stuff? I don't have this problem with electronics, mathematics or electrical technology.

>>12036014
a = pi, b = 1/pi, ab = 1

>>12036069
Basically everything sort of advanced about programming is about addressing problems you would have if you just did it the naive way. If you haven't run in to those problems yourself and they don't specifically outline the motivation it's just going to sound like nonsense.

>>12036069
You will never get a good grasp of programming if you try to "learn" it per se, you need to try to use it for something. Come up with a problem like batch text processing, adding numbers, implement some kind of math function or numerical method that can spit out a list of numbers that you plot in Excel or something. Break the problem down into as many individual steps as you can think of, then try to implement those steps one by one sequentially.

i saw a proof the other day that at least one of [math]e+\pi[/math] and [math]e\pi[/math] is irrational. here is a basic rundown of the proof, as i understand it:
we start with it given that [math]\pi[/math] cannot be expressed as the solution to a quadratic with integer coefficients. now, consider the polynomial [eqn](x-e)(x-\pi)=x^2-(e+\pi)x+e\pi[/eqn]we assume that both [math]e+\pi[/math] and [math]e\pi[/math] are rational[eqn](x-e)(x-\pi)=x^2-\frac{a}{b}x+\frac{c}{d}\\bd(x-e)(x-\pi)=bdx^2-adx+cb[/eqn]since this quadratic has a zero at [math]\pi[/math], we arrive at a contradiction, and our assumption is false.
now, my problem with this proof is that it didnt use [math]e[/math] at all, [math]e[/math] was just some number, and if im not mistaken the proof is still valid for any (real, nonzero) number and [math]\pi[/math]. in fact, since [math]e[/math] is transcendental as well, the proof is valid for any number and [math]e[/math]. could you generalize the proof completely, and say that for any given real number [math]t[/math] that cant be expressed as the solution to a quadratic with integer coefficients, there exists is no real, nonzero number [math]r[/math] such that both [math]t+r[/math] and [math]tr[/math] are rational? am i retarded?

>>12036067
oh right, I was thinking of it like gif related. Which works I guess as long as you know which quadrant is positive and negative.

>>12036089
you got me

>>12033743
what do you mean by in this specific example? Isn't the tan function always the same in that way?

I'm self-studying basic vector calc. How does one reconcile between the definition of the divergence as the sum of partial derivatives [math]\sum_{i} \frac{\partial F_i}{\partial x_i}[/math], and the coordinate-free definition as the limit of surface integrals [math]\lim_{V \to 0} \frac{1}{\mathrm{vol}(V)} \int_{S(V)} \langle F, \hat{\mathrm{n}} \rangle \mathrm{d}S[/math]?

How to intuitively see that the two notions measure the same thing? The latter definition seems like a natural concept, whereas the first (i.e. sum of partials) seems... bizarre.

I have an exercise that says the following:

'The position of an airplane that's flying at an altitude of 5km, is situated at 1.5km North and 2.5km East'

i have to draw this in a three-dimensional space. i'm new to three axes and decided to locate the airplane with these coordinates [math](2.5, 5, 1.5)[/math] right?

The thing is, in one part of the exercise it says: 'In which angle ([math]in regards to the North in the horizontal plane[/math]) do we see it?'

does this imply that the horizontal axis [math]y[/math] should be 1.5km ? Is the [math]x,y[/math] axis in a three-dimensional space still [math]x = West/East[/math] and [math]y = North/South[/math] ? i mean, should the actual coordinates be [math](2.5, 1.5, 5)[/math] ?

I have an exercise that says the following:

'The position of an airplane that's flying at an altitude of 5km, is situated at 1.5km North and 2.5km East'

i have to draw this in a three-dimensional space. i'm new to three axes and decided to locate the airplane with these coordinates [math](2.5,5,1.5)[/math] right?

The thing is, in one part of the exercise it says: 'In which angle (in regards to the North in the horizontal plane) do we see it?'

does this imply that the horizontal axis [math]y[/math] should be 1.5km ? Is the x,y axis in a three-dimensional space still [math]x=West/East[/math] and [math]y=North/South[/math] ? i mean, should the actual coordinates be [math](2.5,1.5,5)[/math] ?

>>12036111

You are correct; the proof is valid for any [math]t \in \mathbb{T},[/math] [math]r \in \mathbb{R}[/math] (it still works for [math]r=0[/math], but is trivial). However, if [math]r[/math] is algebraic it's not particularly interesting because [math]t+r[/math] and [math]tr[/math] (provided [math]r \neq 0[/math]) will always be transcendental.

An elective I'm doing is on bioethics, not super /sci/ related but Idk where else to ask. Which essay topic should I pick?

On what basis should life-saving medical resources (e.g. ICU beds) be allocated in times
of acute scarcity?

One prominent defence of the freedom of movement restrictions imposed by many
countries during the COVID-19 pandemic has been the paternalistic argument – i.e. the
claim that such restrictions are justified on the grounds that they promote the interests of
the persons upon whom they are imposed. Explain this argument. Does it succeed?

Suppose a safe and effective COVID-19 vaccine had been developed. Would states be
justified in compelling citizens to get vaccinated?

Several criticisms have been raised to Daniels’ approach to distributive justice in
healthcare and the social determinants of health. Write a response which (a) explains
Daniels’ view, (b) explains one such criticism, and (c) evaluates whether this criticism is
ultimately persuasive.

I feel like the 4th one is a red herring since we haven't covered any of this dude and desu i dont even know who he is. Thinking 1 or 3. I don't see how this is related greatly to a medical degree but here I am.

>>12032595
Man I can see what you mean. I'm looking at biohack.me and the mods really like to suck themselves off. Their privacy policy and code of conduct is pretty lulsy though.

>>12036292
For V take a cube. Then the normal vectors and the integral are easy to compute and you'll end up with some kind of difference quotient converging in limit to the derivatives in each direction.

>>12036046
why not r^2? that's more commonly what dA is in spherical coordinates. SO when doing the integal, would I just substitute r=2, and evaluate? this method seems brainlet friendly

>>12033507
OK, still trying to wrap this problem up. So I have
[math] |\partial_\phi r \times \partial_\theta r | = \sqrt{\sin^4\phi+\sin^2\phi\cos^2\phi}=4\sqrt{\sin^2\phi}=4\sin\phi \\
[/math]

And is my integral then just
[math]
\int_{\frac{pi}{6}}^{\frac{pi}{3}} \int_0^{\frac{pi}{4}} 4\sin\phi d\theta d\phi
[/math]
?

>>12036786
I guess I just don't really get why the cross product of the partial derivatives forms the integrand. I think that maybe I've found [math]dA[/math] but that my integrand is still missing. Am I worong? is this my integrand?

>>12036786
Here is the whole question rewritten if any anons want to check this, mostly I want to check to see if my integrand was actually set up right, and that [math]dA[/math] is correct. see pic related

We note that our radius is $p=2$ and find the integrand as the cross product of the partial derivatives:
[math]
\partial_\phi r = 2(\cos\phi\cos\theta,\cos\phi\sin\theta,-\sin\phi)\\ \partial_\theta r = 2(-\sin\phi\sin\theta,\sin\phi\cos\theta,0)\\ \partial_\phi r \times \partial_\theta r = 4(\sin^2\phi\cos\theta, -\sin^2\phi\sin\theta, \cos\phi\sin\phi\cos^2\theta+\sin\phi\cos\phi\sin^2\theta)\\ |\partial_\phi r \times \partial_\theta r | = \sqrt{\sin^4\phi+\sin^2\phi\cos^2\phi}=4\sqrt{\sin^2\phi}=4\sin\phi \\
[/math]
So we have our integral as:
[math]
\int_{\frac{\pi}{6}}^{\frac{\pi}{3}}\int_0^{\frac{\pi}{4}} 4sin(\phi)d\theta d\phi
[/math]

>>12036821
lol

>>12036824
what

>>12035104
no, the only "gravity" you feel is when you're in contact with the cylinder.

>>12036827
The fact that you don’t understand how anything works and are begging for help on a routine calculation is funny to me.

>>12036292
see
>>12036616
how I explain it to my students is, I first make the argument that the net flux of a field flowing out of a closed surface can be used to represent a source (or a sink if negative, or neither if zero), and show how one calculates the net flux via the surface integral. Then, we ask if we could approximate that amount of net flux per unit volume instead of per surface area then obtain the flux by adding up that flux-per-volume, since in general volume integrals tend to be easier to solve, or at least set up.
Once we accept that approximation, we take it to the limit of small V, and see that divergence theorem pops out of it and that the correct form of the vector field we were calculating the flux of in a surface integral becomes the sum-of-partials (the divergence) in the equivalent volume integral. In other words, the divergence tells you the net flux "leaving/entering/passing through an infinitesimal point".

>https://en.wikipedia.org/wiki/The_Know-It-All
Using the abode challenge as a start:how can I become the SMARTEST, or at least,among the most cultured/learned people alive?
maths? chemistry? medicine?
What fields do I need to study, to which degree,for how long? Im a neet so im rife with free time

Repost from previous. Anyone?
>>12009455

>>12036828
actually on second thought this isn't entirely true what I'm saying.
there are coriolis forces, euler forces, and centrifugal forces that complicate things.

however I can say for certain that "gravity" does not linearly decrease to 0. the gravity is an apparent force that results from the centripetal acceleration of objects on the cylinder.

>>12036821
dude, you seriously need to go through a book or something. you've been asking the same question for a few days now. knowing the answer to this question won't help you apply it to future problems, you need a better grasp on the methodology.

>>12036845
I'm aware, and I will. But I have deadlines to meet presently, so I just put that problem on the backburner and posted. I fully apprecitate my own need to actually reread and do problems from that chapter, and perhaps the neighboring chapters as well, and plan to do so. But presently I just have to optimize for cranking out soem last minute submissions asap.

>>12036777
Yes sorry, i meant r^2 sin(theta) dtheta dphi. It's brainlet-friendly because it's trivial to calculate the volume/surface area of a solid in its own coordinate system - spheres easy in spherical coordinates, cylinders easy in cylindrical coordinates, boxes easy in rectangular coordinates. You're being told the surface area you're looking for is of a sphere, so the position vector mapping out the points on the sphere you are given isn't really needed - instead, you just integrate the spherical dA over the constant limits you are provided, and r = 2 because the magnitude of the given vector is 2, therefore the sphere it describes is a constant radius of 2.
>>12036786
>>12036821
...I suppose it also depends on what you refer to as phi and what is theta, it seems like your theta is my phi and vice versa, so dA is actually
r^2 sin(phi) dphi dtheta. Your steps are correct, since this is what you obtained. What you've done here is effectively set up the problem in <x,y,z> coordinates and transformed it to spherical, but you should get comfortable with the idea of just setting these types of problems up in spherical/cylindrical coordinates from the beginning since these shapes are so ubiquitous.

>>12036838
Pretty sure split phase and two phase power are pretty much equivalents of one another, worded differently depending on how they are generated. A two phase generator generates two lines 180 degrees out of phase (as would a 3 phase, 4, 5, ..., etc), but a split phase is called that because a single phase gets split in half by a transformer with a grounded center tap on the secondary.

Say i have the coordinates of two vectors [math]\vec{A} = (30, -20)[/math] and [math]\vec{B} = (60, 80)[/math] and i want to make a vector that starts in the point [math]\vec{A}[/math] and finish in point [math]\vec{B}[/math] how can i know the module of the vector i want to build, by adding the two points?

>>12036894
[math]\sqrt{(x_B-x_A)^2+(y_B-y_A)^2}[/math]

>>12036894
that vector you're looking for is just B - A, look up vector addition for how pictures on how to visualize this easily.

>>12036894
bro you've asked a similar question already. just read the first chapter of any linear algebra book, this shit is so ridiculously basic.

>>12036860
I'm not fucking with you when I say that you'll get your answer quicker and less ambiguously by finding the appropriate chapter on "surface integrals" in a multivariable calc textbook.

>>12036912
I know, and I agree. Generally I try and stay a couple weeks ahead of the course, because I know I go full retard mode when it's crunch time; my brain just tries to go for a hail mary win condition when ti's almost always faster to start from the bottom and work my way up. I got a little overwhelmed this week cuz the final was actually a week earlier than the courses schedule had said.

But that's over with now, and I'm going to spend the next month before fall term casually going over what I learned/was supposed to learn.

>>12036881
>are pretty much equivalents of one another
They’re not though. True two phase uses two transformers and a line coming from each and the most common phase separation is 90 degrees. Split phase power sources cannot start motors on their own, two phase can.

I had an interview on thursday and I sent an email thanking them for their time.
Should I send another email on monday asking what the status is or is that too soon? I really want this job, it seems so easy and laidback for an engineering position.

>>12036838
> Are the legs in a split phase power systems necessarily an inverse of each other?
Yes. Split-phase is obtained from a single transformer winding with the two phases connected to the ends of the winding and the neutral/common to the centre tap.

"Two-phase" generally refers to two phases which are 90° apart, i.e. the same thing as "four-phase" or "quadrature".

is the relationship between the diameter of a body and it's angular momentum linear or parabolic

Can someone give me a worded definition of what a derivative or differentiation actually is? I want to know what it is in plain English

>>12036837
Browse 4chin

>>12039552
>angular momentum
You mean rotational inertia?
This is like asking the relation between a body's diameter and its velocity.

>>12040083
How a function responds to small changes in the variable on which it depends

Would particle size change how fast a powdered/ground product would dry out in a 40% vs 55% humidity environment? How fast would it "dry out" for say 1kg?, and what is the bottom limit of drying?

Are there any good books about space I can get my mum to read? She's interested in space & planets but her understanding of maths is like high school level so I need something with few equations in it just stuff explaining how things work

>>12035959
All Science Teachers Crazy.

>>12039220
So in a split phase there’s no separation of the legs correct, they’re simply 180 degrees apart due to the construction with no way to change that? How are the phases separated in a two phase system, to make them 90 degrees apart? If you instead separated the phases in the two transformers by 180 degrees, would it be functionally the same a split phase system or would you still need two neutrals (or one double sized neutral) sense they’re independent phases?

>>12040361
> they’re simply 180 degrees apart due to the construction with no way to change that?
Correct.
> How are the phases separated in a two phase system, to make them 90 degrees apart?
Most two-phase is generated electronically, but you can do it with a generator where the coils are perpendicular.

Does the linear line always have to go through the bottom and the top to get an average?

>>12040619
>linear line
no, a line is defined completely with just two points. these can be anywhere.
if you're talking about a line of best fit, then no. it does not have to go through the extreme points.

>>12040628
Thanks Anon. Can you explain the formula? I'm doing this through Khan Academy and it doesn't explain the formula at all and I'm completely lost. (And math isn't my strong suit...)

>>12040700
>Can you explain the formula?
What is your problem?

>>12040700
this looks like you're just supposed to be estimating based on which line fits the best.
I think you can tell which of those three lines fits the best. once you pick which line it is, find the slope by calculating the change in y over a certain change in x, and then add the value of the y-intercept to get an equation of the form y=mx+b

>>12040714
>What is your problem?
The formula. This is the first I've seen it. I got no introduction on which numbers go where, etc.

>>12040720
>find the slope by calculating the change in y over a certain change in x, and then add the value of the y-intercept to get an equation of the form y=mx+b
Sorry, that went right over my head. Are there calculators that can do this or do I have to do it manually? (Again, I was always terrible at math and only really got the basics up to division.)

>>12040737
just watch this
https://www.youtube.com/watch?v=1wekohJ5nqA
you need to know the process

>>12040754
Thanks Anon. Do you have any thing that is a few steps before that video? I still didn't get it.

If it helps - I just started taking the high school stats course on Khan Academy. I thought that it would explain this formula in the course. I guess I need to backtrack to understand it better. Should I be looking at fractions or?

>>12040834
you need to look for something that's probably on the level of 8th grade math. I think it's sometimes referred to as "math II." it will likely be what's just before geometry or algebra
https://www.katesmathlessons.com/intro-to-slope-intercept-form.html

>>12040839
Thank you Anon. I'll brush up on my grade 8 (hahahaha.....) skills and then try it again.

Any risk from mixing Dimethyl Sulfoxide with methanol?

>>12040839
Sorry, me again. Wouldn't this be 3/3 since it's three boxes across and three up?

>>12040921
yes, the slope of this line would be 3/3=1
the example they listed in text is not for that image

What happens if you bombard an electric field with a electro-magnetic wace (vertically polarized e-field)???

>>12040944
the total electric field is the sum of the initial electric field and the oscillating field due to the EM wave

>>12040944
wave

>>12040923
thank you Anon. What about this one? She switched the way she did the Rise and Run. :/

>>12040875
Don't be discouraged. Im not the previous anon but when it comes to math and arithmetic, you must go as far back as truly necessary to find the ground you are comfortable on and move forwards again from there. If that means you're comfortable with 7th grade math but not 8th grade math, then you must go back to 8th grade and work from there. You will not catch up by trying to skip ahead to college level stats and calculus, you need the practice on the earlier material first and foremost.

>>12040944
Superposition in most materials. Most materials and air/vacuum are linear, so a wave and a static field will not interact at all.

>>12040952
she's doing it the same way. if you start by going right versus start by going up you get the same answer because you always do the vertical/horizontal

you go up 2 and over 3, so this slope is 2/3

>>12040948
Yea
But: An electric field, is an energy transfer, a EM wave is particle transfer;
And the magnetic field from the EM over time is 0, the same as the EM e field. But if you introduce the "seperate" e field, the EM e field is manipulated/changed, thus the particle is on a different trajectory, and thus interacts differently with the magnetic field...

I just don't quite get it. Yes I now how a EM wave is "drawn" and theoretically changes the e field vector if interacted with the separate e field but read my concern in the first paragraph.

I tried to understand it with the maxwell heavy sides but ether Im a brainled or the equations are corrupted, the latter would explain why quantum mechanics is so hard/not quite understood

>>12040990
either

>>12040990
bare fields do not interact with each other
if you want to calculate the total field from a collection of point charges, you sum up the fields from each charge.
if you have an oscillating field E(t) and a static field E0, then the total electric field is simply E0+E(t)

>>12040962
Thank you Anon. I think I'm just getting a bit overwhelmed with new information. I put a hold on an introductory stats book at the library that I can hopefully pick up tomorrow.

Big thanks

>>12041004
This book

>>12041001
That is, if the e field and the EM e field "go in the same direction"
But if you blast the e field 90 degrees from the side...
like im this picture>>12040944

>>12041004
intro stats will likely be above your level, by the way. you should focus on getting through the material at the level of the questions you've been asking beforehand.

>>12041014
no. you still add them, but now you just have to be careful about what you're adding
if the static field is polarized along x and the oscillating field along y, then the total E-field is equal to:
[math]E_{\text{total}}=E_0 \hat{x}+E(t) \hat{y}[/math]
to get the magnitude of the total E field you take the square root of the squared sums of each component.

>>12040876
Pls respond

My last try. Don't want to annoy you.
If the EM wave and the e field collide, that would theoretically result in an oscillation in the x direction (resulting e field would now oscillate in the direction of the original e field??).

But what happens with the EM mag field?!

>>12041020
thank you Anon. I really appreciate all the help I got today.

>>12041085
the oscillation direction will not change at all. I don't know what initial directions you're talking about, but literally just add the contributions from the two effects. don't think that they interact with each other because they don't.
fields don't "collide" in the sense that you're thinking about. add the contributions separately, and the total e-field is the sum (with directions considered)

>twice in the video demonstrating reactions the presenter referred to KI, starch, HCl, NaHSO3, and NaS2O3 as progressively stronger oxidizing agents
>Supposed to observe when a reaction occurs with the above chemicals and KMnO4, H2O2, KIO3, K2Cr2O7, NaNO2, CuSO4, and FeCl3 and figure out in each case which chemical was the oxidizing agent and which was the reducing agent
>google these reactions; apparently they're all redox reactions
>don't know how most of these reactions and half reactions actually go (double replacement? decomposition?)
>table of standard reduction potentials leads me to believe that something like MnO4- is probably the oxidizing agent in whatever redox reaction it's involved in because of how high its reduction potential is, but again the presenter in the video stated that all the chemicals on the OTHER list are oxidizing agents
I'm so fucking confused.
Okay, here are some actual coherent questions someone could answer. Suppose potassium permanganate reacts with sodium hydrogen sulfite in a redox reaction. Is the potassium permanganate the oxidizing agent and sodium hydrogen sulfite the reducing agent? Is it correct to name the whole molecule as the reducing/oxidizing agent, or just one of their ions respectively?

Stupid question, but what am I doing wrong:
If I were to calculate it with conditional probability I'd get (10/36)/(5/6)=2/6 , but if I were to try get it by taking the complement of not getting it whilst not having duplicates I get 1-((5/6)*(4/6)+(1/36)=15/36=5/12

>>12041885
Never mind, no clue what I was thinking there, the answer what I was doing wrong became very obvious after posting.

are uterus wall clamped together or is just a semi "rigid" bladder?

wikipedia doesn't really help

Hi, I'm struggling with a linear alg thing, also english isn't my first language so pls bear w/me.
I have two subspaces defined by generators, say < v1, v2 > and < w1, w2> and a random vector u = (u1,u2,u3,u4)

How do I figure out if this vector 'u' belongs to the sum V+W?

>>12041962
What I did was to form a system of both s+t and u as the extended part of the matrix, and attempt to solve, there are some variables within the system annoying me a bit, but is that the correct approach?

Can you guys recommend a good book on statistics and/or probability? I started studying machine learning, all they teach are fucking python functions, but I want to know the mathematical background.

>>12041962
figure out if the non-homogenous system of linear equations

u = a*v1 + b*v2 + c*w1 + d*w2

in variables a,b,c,d has a solution

>>12032812
>>12033131
>the state of /sci/
[math]w=ck[\math]
[math]v_{\text{group}}=\frac{dw(k)}{dk}=c[\math]
[math]v_{\text{phase}}=\frac{w(k)}{k}=c[\math]

You should know this

>>12042474
[math]\omega=ck[/math]
[math]v_{\text{group}}=\frac{d\omega(k)}{dk}=c[/math]
[math]v_{\text{phase}}=\frac{\omega(k)}{k}=c[/math]

>>12042460
Try https://faculty.marshall.usc.edu/gareth-james/ISL/ISLR%20Seventh%20Printing.pdf for a book on machine learning concepts from a statistics point of view. It assumes some familiarity with statistics language at least but otherwise it starts from the start and doesn't really get bogged down in technical crap.

>>12042460
check the wiki page there are recommendations for cstards in need of stats training as well as those for mathfags. this is why the autist needs to come back. I would remake the copy pasta for the OP's but I don't care enough about this board to do that myself.

I don't get why the second derivative is < 0 at a maximum. Why isn't it always zero, since the first derivative is a straight line?

>>12042677
The first derivative cannot be a straight line otherwise that would mean the function is linear.
Think of it this way: at the maximum the first derivative goes from positive to negative, thus it is necessarily decreasing hence why the second derivative is negative.

>>12042677
The straight line that you're talking about is just some straight line tangent to the curve. At the very specific point that you build your straight line it is equal to the first derivative but that's not true anywhere else -- at any other point you would need to make a new tangent line. The first derivative is a function that at every point takes the value that the tangent would have if you built it at that point.

A good exercise for seeing this is to take some nicely shaped cubic function (blue) (this is just whatever cubic function wolfram alpha suggested so it's kind of cramped) and look at the behaviour of it's first and second derivatives (purple and brown, respectively). Start with the second derivative - pick some points and check that the value of the brown curve is the slope of the purple one. Then check that the value of the first derivative (purple) is the slope of the blue curve. Then go back and look at how the change in the slope of the blue curve relates to the value of the second derivative -- it's turning downward in the region where the second derivative is below 0 and turning upward where it is above it.

>>12042768
>>12042796
Thanks it just clicked, makes total sense. For some reason I was thinking the second derivative is the derivative of the tangent line. The graphical explanation in >>12042796 made it very easy to understand.

>>12042768
For example, look at [math]e^{-x*2}[/math] at x=0.

>>12042768
Although you can have a non-constant function with all derivatives at x=0 equal to zero. I can't think of a formula off the top of my head, however.

>>12042821
You can't have an analytic function (other than f(x)=0) for which all derivatives are zero at a point, as that would mean that all coefficients of the Taylor series are zero. For f(x)=k*x^n, all derivatives up to the (n-1)th are zero at x=0, but the nth is equal to k*n!.

>>12042855
Right, but not all functions are analytic.

>>12042469
Yeah, basically what I was attempting to do, problem was that T had some free variables? and the manipulation was a pain in the ass.
Thanks

How do I find the radius of convergence from a series?

>>12042855
who's talking about analytic functions ?

>>12043023
the guy doing calc 1, probably

Can some1 explain me the gist of complex analysis in 1-2 paragraphs? Poles, analytic functions, series representation, radius of convergence, residues etc

>>12043088
Oh, continuity too

I'm thinking of going to grad school and snagging a PhD since I got my BS and never touched my GI bill or FASFA. I'm going deciding between Neuro and Psych (med and non med). My BS is in mathematics, which is easy as hell for me, but I have a passion for the human mind, specifically dreams, giftedness, and growth and development. The cognitive and mental aspects of the mind interest me more than the neurological and physiological; however, I don't want to neglect them and see all the potential for discoveries bridging the two. Any suggestions? I also dig physics, but only formally studied it briefly. Fitness is super interesting as well to me if that points to anything
I have enough money and that's not what this is about. If things got that bad I have a few fallbacks. This is more something I want to do that feels right.

Lets assume there is this reaction: A B + C, with Arrhenius reaction rate of D mol/m3-s.
If I want to find the accumulation of C, should I convert the reaction rate with molecular weight of A or C?

>>12040944
>>12040990
>>12041085
I'm that guy. And I'm back with another stupid, or maybe not as stupid question as yesterday. And I still want to build a hoverboard.

An EM Wave creates both an electric field and a magnetic field.
Now if you orthoginally cross two electric fields you get a magnetic field as well.

Now you have the EM mag field and the produced mag field from crossing the EM e field with the seperate e field

Now what happens when you orthoginally cross two magnetic fields?
Does it indeed produce a (gravitational) force? AKA Anti gravity?

>>12043860
That would mean you have to prove that:
Newton/Power=Magnetic flux density
And if you do all the math to that, what it basically comes down to, is (in units):
Ampere = kg*m*s^-3
that would mean
Coulomb = Newton
mhhhhhh

>>12043860
bro I really don't know where you learned your E&M from but it's just not correct
>Now if you orthoginally cross two electric fields you get a magnetic field as well
can you explain this? this is not true. unless you're talking about something different.
>Now what happens when you orthoginally cross two magnetic fields?
>Does it indeed produce a (gravitational) force? AKA Anti gravity?
absolutely not.
magnetism and gravity are mediated by separate forces. there is no way to have them interact.

>>12043122
Do you have a specific topic that you want to research? Does your desire for a PhD outweigh being a labrat for 5 years or more?

>>12042992
Ratio test.

Why are some proofs fun and some unfun? I'm trying to figure out what makes some proofs fun and others boring.

>>12044028
fun is subjective. look inside yourself

>>12043942
Intellectual giftedness is definitely up there. I've always had vague ideas about helping people overcome mental health that I just recently learned lines up with Dabrowski's Positive Disintegration. Mixed feelings about the labrat thing. If it's something I'm passionate™ for I wouldn't mind, but I know how political academia can be, and is. I'm honestly just tired of going through life doing what's "effective" instead of what I want to do. I want to make a difference with this, I just hope I'm not romanticizing this.
I definitely have the aptitude and finances for this. It would definitely be more interesting than wageslaving and "retiring" at 40 with nothing to show but money.

>>12043889
okay. I will have to do more reading.
I thought of just trying out what happens experimentally.
An EM Wave Generator shouldn't be too hard to build. The rest should be trivial.
But I just don't know how much frequency to put onto the EM Wave Generator or what Potential I need for the seperate E-field ._.

>bro I really don't know where you learned your E&M from
I don't know either. Books or the Net.
If you have any book/webside recommendations, I would greatly appreciate it.

blog
I don't have any "formal" education in that field, or remotely to that field. That's why I annoy you here. I aced primary, middle, high, did a two year "industrial engineering and managedment" B.Sc. than worked for 6 months to get some money, became ultra lucky in trading/crypto and now I have enough money to life for the next 300 years (all money realized, Believe you me, 8 times 0, not in the lower half). Seen most of the world, and now, I just want to build cool stuff. Already build one of those DIY Kitfox Bushplanes. But always mired at the McFly Hoverboard or a Flying Car.
So I looked it up, and somehow came to a patent (US 2006/0145019 A1) that was released in the UK under some freedom of information act, and in which they orthoginally cross an e field with an EM field (vertically polarized e field).
So I just want to understand it. In a few day, I should be back at home. Already ordered some silver, copper and alu plates, different thicknesses of copper wire (both insulated, and not) a frequency generator, all the machining tools I might need. A few of those Voltmeters, Amperemeters, Oscilloscope, etc.
Now I need to build a good electrostatic generator and an EM Wave Generator to test it out. What exactly do I use to test a field? One of those copper rolls on a stick, if it spins there is a field? Read that as an analogy to one of the maxwell heavy sides.
/blog

>>12044158
you should at least be able to read through and understand Griffith's Electrodynamics at the bare minimum before asking questions about this. and you probably should look into a circuits book if you're planning on building something.

>good electrostatic generator
that's just a charged plate
>what exactly do I use to test a field?
depends. testing oscillating fields is easy with an EMF meter.
testing static E fields is very complicated and inaccurate. testing static B fields is much easier, magnetometers are commonplace
be careful, working with high voltage to produce static E fields can be dangerous.

I'll end with this: you won't build a general-purpose hoverboard, because it is not possible in this sense. There is no force coming from the earth to push you upwards, and you cannot create "antigravity" as you've previously referred to.
The only thing that would potentially work is by having a specialty flooring material that interacts with your hoverboard. if you produce a magnetic field that points upwards, you could make something that floats by having an opposite-oriented magnetic field produced by your hoverboard.

>>12032464
Engage your mind, all across your neocortex, to build a thoughform representing the sensation of particular substances emitted from the object in question, suspended in the air and intercepting your olfactory receptors

>>12043122
Do mathematical/theoretical neuroscience bro, if you're good at math you'll be bored by the neurobio/cell bio aspects of neuro. Otherwise do neurophysics but the prereqs for graduate programs are a bit more weighted towards biophysical background there and it might be harder to into.

How do you keep your handwriting neat when there's a billion subscripts and superscripts?

Libraries are closed and I don't know where to seriously study. My room is full of distractions (which I can't eliminate) and I don't have any other place in the house. How do you guys do it?

>>12044966
idk, you can always put some white/rain noise, get some nice headphones if you can. Aren't cafes open in your part of the world?

Am I doing something wrong or is the website broken?
>Question: What is 3.2 ×10^10cm/s to ft/s
After doing the conversion to meters and then to feet I get 0.10498688*10^10 ft/s. I am getting the same thing when I just look up the conversion and when I do it by hand with my calculator.
But my homework website keeps saying it's wrong.

>>12044982
Noise isn't the problem, but all the stuff that is in my room (computer, bed, books, musical instruments) that can't even be moved out of my field of view. And the fact that I always used my room to do everything but study, so it's hard to focus.
>cafes
Yes but they aren't used much for studying and they are usually noisy. If I went there with books, pen, paper and my laptop they'd look at me like I was an alien

>>12044995
you have to rewrite the scientific notation
0.1*10^10=1*10^9

Math question here.
Hey bros, college is starting again and I'm already fucking stressing despite the fact that it starts the day after tomorrow.
I took Calculus 2 with an introduction to Vector Analysis which contains the section usually introduced in Calculus 3: Equation of Lines and Planes in Space.
That section is my worst section and my professor had said to my class last semester that this section is something that just 'hits out of nowhere' and that 'you would understand it once it does,' is it true?
And is there any ways to better understand the topic?
Or any advice in general?
I haven't done much practice problems because I always go blank but that might be because of my homework problems always going from level 1 to level 10 to level 100 instantly which trips me up.
I can do something like
>Find the equation of the plane through the origin and perpendicular to the vector X,Y,Z
But when it comes to something like
>Find the parametric equations for the line through the point X,Y,Z that is parallel to the plane [plane equation here] and perpendicular to the line [line equation here]
I just blank out

TL;DR
How do I 'get good' at Equations of Lines and Planes because it's apparently the fundamental of Calculus 3 and that if I don't know it, I'd fail. I'm terrible at it (partly due to barely any practice) and is seeking advice.

We’ve heard the controversy that happened over common core math, but what was math like before “New Math”?
>75 - 29
>>Common Core (Count up to larger number, then add the steps)
>29 + 1 = 30
>30 + 5 = 35
>35 + 40 = 75
>1 + 5 + 40 = 46
>>New Math (Borrow from next place then subtract columns)
>75 - 29 -> 5-9
>6(15) - 29 -> 15-9=6
>60-20=40
>40 + 6 = 46

>>12033073
Yes. A good chunk of universities refuse to transfer Gen Eds or even honor CLEP exams.

test

>>12033073
Mine gave me that same shit stating I needed “Calculus for Engineers” instead of just Calculus. Honestly, take the easy A if you really remember it, and if you don’t, you’ll be glad to have the refresher.

what is applying for a master like?
I applied for some job at a university but the professor said to apply as the ra, master or phd
From what I can see, this is like non-thesis research program where I am basically a programmer(?) with some field knowledge like electronics, mechanical systems or whatever
i have no idea what to think about
i have an interview tomorrow that is supposedly not technical based (yet) and they simply wants to know my interests
i guess i am pretty interested in improving their inhouse graphical programming language? but i cannot muster any interest in developing some corporate DSL GUI programs lmao

>>12045378
I can only speak to phd but I assume masters is similar. The process is quite similar to undergrad except less focus on your holistic life (school, extracurriculurs, volunteering, etc.) and more just your performance in school.
It sounds like you're doing this not in the US? In the US masters is a scam, you have to pay for it. It's not a job. You get a degree at the end of it. The whole situation you're describing seems weird since I don't see why the prof would tell you to apply if you wanted a job.

>>12045389
this is not in Canada and is a paid position, from what I can surmise, they are looking for someone that can program in C++ or something to _Actually_ build stuff
It seems like they have a LOT of stuff to work on including 3d visualization, simulation, graphical IDEs, etc etc
afaik, I will be solely programming, but I honestly don't mind writing papers of what I have learnt or present them
I like doing that too, if the subject is something that I find interesting

>>12045389
this is not in the US and is a paid position, from what I can surmise, they are looking for someone that can program in C++ or something to _Actually_ build stuff
It seems like they have a LOT of stuff to work on including 3d visualization, simulation, graphical IDEs, etc etc
afaik, I will be solely programming, but I honestly don't mind writing papers of what I have learnt or present them
I like doing that too, if the subject is something that I find interesting

>>12045410
well I guess why not get a free degree out of your job? it sounds like the "application" is more like a job application than a typical school one.

>>12045420
that's what I thought too, although I think I am going to do a lot more reading than a typical job (not that I had one to speak of)
does joining the academia first thing out of school a bad thing in the market?

freeform optics or nonlinear optics?

>>12045424
no, academia is generally one of the better places to be right now (during this virus) because it's generally a pretty secure position. and it will give you additional qualifications/connections for what you want to do next.
the only downside is you're delaying the start of your career.

>>12032464
So I was taking an exam to become an engineer in the navy, and on the entire 2-hour/80-question exam this was the only problem I couldn't answer correctly. I tried using the basic chemistry heat equation, but you can't really use it since the mass is changing, and if you differentiating it to account for changing mass, you find that you get the second derivative of heat change so you can't really do anything with it.

So considering this problem shouldn't involve anything complex, I'm guessing this requires either a direct or inverse proportion? Does anyone know if that is true?

>>12045830
1 is the index for the 100F water, 2 is the index for the 50F water, 3 is the index for the final mixture
[eqn]m_1*T_1+m_2*T_2=m_3*T_3 \\
m_3=m_1+m_2 \\
T_3=75 \\
T_1=100 \\
T_2=50[/eqn]
since water's mass is just proportional to its volume (for all intents and purposes, unless this test would be getting into expansion coefficients), you can use volume in place of mass

What would be the most efficent way to extract Cardiac glycoside from Nerium Oleander

how do i solve polynomials
second order i can do with my mind but cant into third order
is there some hack i can use

examples
x^2 - 3x - 4 = (x-4)(x+1) ezpz
-x^3 + 8x^2 - 6x - 3 = ???

I have three servers which each have a cost in ms(amount of time to process a request).
Server 1 = 0
Server 2 = 1000
Server 3 = 2500
Let's say there are 10000 requests.

What can I do to distribute the number of requests among these three servers? Any material or pointing in the right direction would be great.

>>12046437
well obviously you all send em to server 0 since it will do it instantly

>>12046442
That was originally part of the problem; In the event a server reports 0 cost for some reason, how can this be accounted for?

Is there a name for the study of the Arctic?

>>12046458
i dont really know what you're doing and have never balanced servers but if you know the time it takes for em to do a task, for example
100ms
1000ms
2000ms
divide 1 by each amount to get requests/time
10/s
1/s
0.5/s
then just total and send each one its value/total*requests(i cant into words)
lets say you have 10000 requests
total 10/s + 1/s + 0.5/s = 11.5/s
server 1- 10/s / 11.5/s * 10000 = ~8696 requests
server 2- 1/s / 11.5/s * 10000 = ~870 requests
server 3- 0.5/s / 11.5/s *10000 = ~435 requests

if it reports 0ms, you could just send some requests and time how long it takes to finish to get the actual time

>>12046458
but if the requests dont all come at the same time and the servers reporting the cost isnt 1000% accurate you could make a queue for each server and time how much time it takes for it to do shit (queue length/speed)
server 1: 500 requests in queue, completed 200 requests in the last second, total queuetime 2.5sec
server 2: 300 requests in queue, completed 50 requests in the last second, total queuetime 6sec
then add the requests as they come in to the server with the lowest queuetime

ill say it again, ive never balanced servers but this is how i'd do it

>>12032464
How do I learn math(defined as everything from grade school to high school) as quickly as possible?

>>12046649
KHAN academy is the biggest spoonfeed for this

>>12046649
Khan acadamy. Or read and do the exercises in text books from pre-algebra to calculus

Is there an existing term for someone who possesses an abundance of empathy, a full range of emotion with the exception of guilt, and can intuitively model the mechanisms of morality in their mind on a completely detached level, but never, ever engage their conscience and might not actually have one? As in, they can simulate the components of a conscience to a point that it may as well exist, and do not merely have to mimic the conscientious behavior they see in others, but it is something that imparts no emotional pressures to them. Trying to google to confirm a negative is a shit prospect.

How do I prove a polynomial with r roots has a derivative with at least r-1 roots?

Using Rolle I can see how that would be the case if the roots were all multiplicty 1 but then I get filtered

>>12032464
This is full retard but I'm drawing a blank on pretty easy physics shit today.


A football player runs with the ball due north at 4.5m/s (relative to the ground)
While running, he passes the ball at 6.0m/s to a teammate in a direction 30.0 degrees south of east (relative to himself).

Calculate the velocity of the ball relative to the ground.

>>12032464
Could a specific shaped structure made of a pure electric isolator create any kind of effect on magnetic fields or something?

>>12046796
What kind of football?

>>12046835
Rugby ball, air resistance isn't a factor though

>>12046379
Cubic: https://en.wikipedia.org/wiki/Cubic_equation#Cardano%27s_method
Quartic: https://en.wikipedia.org/wiki/Quartic_function#Solution_methods
In general, polynomials of degree 5 and above don't have solutions in terms of radicals (nth roots):
https://en.wikipedia.org/wiki/Abel-Ruffini_theorem

>>12046744
r roots or r distinct real roots?

For the former, a polynomial with r roots has degree r, it's derivative is polynomial of degree r-1 which has r-1 roots (not necessarily all real or distinct).

For the latter, think of the shape of the graph. r roots means r-1 regions between adjacent roots, and each of those is a peak or trough, i.e. the derivative must be zero at some point in that region (possibly multiple points).

Given that it says "at least", I'm assuming it's the latter case. E.g. graph the quartic y=x^4-5x^2-1; this has only two real roots while its derivative has three.

How much does math tutors usually charge for Calculus 3?
(Assuming they're also a professor at the side of things)

>>12047022
This is the exercise. It's real roots I think, but not sure if distinct.
>For the latter, think of the shape of the graph. r roots means r-1 regions between adjacent roots, and each of those is a peak or trough, i.e. the derivative must be zero at some point in that region (possibly multiple points).
Yeye, this is how I did my proof. Thing is it doesn't work (I think) when multiplicity is higher.
Take (x-2)^3 = x^3-6x^2+12x-8. This has three roots (one of multiplicity three). However by my intuition I can only say the derivative has one, and I can't even prove that

>>12032464
Can this be solved without using inequalities? Like construction [math] P(.4 \leq \bar{X_n} \leq .6) \geq .7 [/math] and find the [math]n[/math] that makes the equality hold? I tried to attempt this but I am not sure if [math] \bar{X_n} [/math] follows a bernoulli distribution. Also, I am not sure how I would go about calculating such a probability since it seems to me that [math]\bar{X_n}[/math] does not take on finitely many values.

Any suggestions on what topics to study extra hard for and/or pay a lot of attention to? This is the syllabus for my Calculus 3 class.

>>12046796
find the components of the ball's velocity that are south and east (using trig).
subtract the south component from the north component that is due to the velocity that he's running
total velocity is the square root of the sum of squares of the vertical/horizontal velocities

>>12047453
I'd broken it down with trig already but couldn't figure out where to go from there.
Thanks, that helped immensely.

Anxious as fucking hell for the upcoming Physics 2 and Calculus 2 course, how do I chill the fuck down because all I've heard about the two are horror stories.

Why does undergrad feel like such a scam? Im in my senior year of electrical engineering and Ive only taken three classes with any real value since I enrolled. Ive spent 3 years studying classes that only pretend to be relevant while engineers who actually work for a living barely know circuits and calculus

>>12048720
dont forget to pay for the premium meal plan goy

What's the non-meme way to teach myself chemistry?

Simple question but fuck me I am struggling over here
x3y = -4 => x(x2y + 4) = 0
...right? Can someone help the brainlet here?

>>12049184
x^2y = -4 => x(x^2y + 4) = 0
I meant power, fuck!

>put a blackhole in a blackhole
>what next?

>>12049184
>>12049191
I guess that isn't as clear either and I fucked up the power
x^3 * y = -4 => x(x^2 * y + 4) = 0

There... I think?

>>12049196
bigger black hole

>>12047158
If [math]X_i[/math] are iid Bernoulli, then [math]X_1+\dots+X_n[/math] is binomial, takes over values from 0 to n, so the sample mean [math]\overline{X}_n[/math] is almost binomial, taking values [math]0, \frac{1}{n}, \frac{2}{n}, \dots, \frac{n}{n}[/math]. But this means you can compute probabilities directly(with a computer).

>>12047365
I think partial derivatives are straightforward. People seem to have trouble with double integrals, and in particular, setting up bounds for some regions. People also screw up cylindrical and spherical coordinates if that's the first time you are doing it.

>>12049197
However you write it it's wrong. When you expand , x(x^2*y+4) you get 4x. You can't realistically simplify that expression. Either x^3*y=-4 or x^3*y+4=0; anything else will be either more complex or just wrong.

>>12047875
Prepare that these classes might be hard by studying ahead of time. Use Khan Academy or whatever to learn the material before the class, and then use the class as a review, so you'll be extra prepared.

I'm taking abstract algebra this semester and I am curious as to why relations and as a consequence equivalence relations are so important in math? I understand what they are, but I think i'm missing how they play an important role in math, and why we study them.

I have [math]B=\{x \in \mathbb{R} \ | \ x^2 + x + 1\}[/math] and I'm trying to find its infimum. I've established that [math]\frac{3}{4}[/math] is a lower bound for the set and I'm trying to show that it's the greatest lower bound. So, I take [math]\epsilon > 0[/math] so that I have [math]\frac{3}{4} < \frac{3}{4} + \epsilon[/math]. How do I proceed from here?

>>12049697
take the derivative

>>12049697
It seems that you mean [math]B = \{ x^2+x+1 \mid x \in \mathbb{R} \}.[/math] Anyway, [math]\frac{3}{4}[/math] is in your set, so the lower bound is a minimum and therefore the infimum.

>>12049767
That makes sense. Guess I was overthinking it. Thanks, anon.

>>12049391
Thank you kind anon.

>>12046379
axxx+bxx+cx+d=0

[math] \displaystyle
S=2b^3-9abc+27a^2d \\
T=b^2-3ac \\
Q= \sqrt{(2b^3-9abc+27a^2d)^2-4(b^2-3ac)^3}= \sqrt{S^2-4T^3} \\
C= \sqrt[3]{ \frac{1}{2}(Q+2b^3-9abc+27a^2d)}
= \sqrt[3]{ \frac{1}{2}(Q+S)}
= \sqrt[3]{ \frac{1}{2} \left ( \sqrt{S^2-4T^3}+S \right )} \\
x_1= - \dfrac{b}{3a}- \dfrac{C}{3a}- \dfrac{b^2-3ac}{3aC} = - \dfrac{b}{3a}- \dfrac{C}{3a}- \dfrac{T}{3aC} \\
x_2= - \dfrac{b}{3a}+ \dfrac{C(1+i \sqrt{3})}{6a}+ \dfrac{(1-i \sqrt{3})(b^2-3ac)}{6aC} \\
~~~~ = - \dfrac{b}{3a}+ \dfrac{C(1+i \sqrt{3})}{6a}+ \dfrac{(1-i \sqrt{3})T}{6aC} \\
x_3= - \dfrac{b}{3a}+ \dfrac{C(1-i \sqrt{3})}{6a}+ \dfrac{(1+i \sqrt{3})(b^2-3ac)}{6aC} \\
~~~~ = - \dfrac{b}{3a}+ \dfrac{C(1-i \sqrt{3})}{6a}+ \dfrac{(1+i \sqrt{3})T}{6aC} \\
[/math]

>>12049676
equivalence relations are everywhere especially in abstract algebra. they will be everywhere when you study groups in abstract algebra, you will see their importance soon enough

What’s the point of Taylor series? Can’t hard functions just be manipulated on a computer? Why the need to approximate them ?

>>12050130
The overwhelming majority of integrals and differential equations that show up in the real world cannot be solved analytically, so we need to use numerical methods and Taylor series come up as ways to approximate functions. Also, it's easier to work with polynomial terms than trigonometric or logarithmic ones.

[math]\int x^x dx[/math] is an example of something that can only be solved via Taylor expansion, also known as the sophomore's dream.

Where is potential energy?
If an object falls toward a black hole and the mass of the black hole decays during the duration, for instance.

Any biologist present can help clear this doubt?

Ok so i was reading on some papers about human telomerase reverse transcriptase, and this group
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3449956/pdf/10616_2004_Article_5123.pdf
managed to "Immortalize cells"

and as i kept reading this kept on coming up, cell immortalization
of course i know this refers to cultivated human cells and this seems to be promising in cancer research...

but couldnt you also use hTERT to immortalize human cells in vivo? is it even logistically feasible? is it possible even?
it shouldnt cause cancer-related issues, all it should do is allow for indefinite lengthening of the telomeres, which in my limited understanding of human biology equals extended life-span

i am just too stupid to get something here or are all bioquemists not seeing this?

>>12050130
How the fuck do you think you're manipulating them on the computer?
(The answer is not usually Taylor series because much more sophisticated approximations beyond what you learn in freshman calc exist. But the moral of the story is the same: approximations are really the only things we actually have access to.)

>>12050130
>Can’t hard functions just be manipulated on a computer?
how the fuck do you want to do it ?

>>12049676
They partition a set completely and cleanly. Not only that, but they partition the set with respect to the underlying structure of the given equivalence relation. This is incredibly useful for managing large, complicated sets when you care more about certain properties of the elements rather than the elements themselves.

>>12049676
relations are just a very handy tool, they're more "useful" than "important". you're question is a bit like asking why are bricks important, answer is go see a house.

How long will it take me to master 9th & 10th grade mathematics if I am reasonably motivated? My Bacalaureate exam is coming up and I don't remember jackshit from earlier years so I figured I might as well start studying now.

>>12050179
It isn't anywhere and it doesn't have to be. Think about the word "potential". If some force were to perform work on some thing its kinetic energy would change by delta U. There is the potential for the thing to gain that amount of energy by the process you're considering.

Is it worth it to get a Math degree?

I had a shower thought today I'd like an opinion on.
If you've ever taken off your clothes in the dark as a hairy person, you've witnessed/heard all the static that comes with that action.
Now surely, the simple rustle of clothes against body hair as you move during the day creates a fair amount of static, that you discharge uknowingly and continuously.
My thought was, could this constant discharge of a tiny amount of current cause harm, and if it can could it explain why men (more body hair) have more heart attacks than women?

anyone have any good text recs for linear programming?

>>1204969
You can just plug in x=-1/2 and get 3/4 out. So there can't be a minimum greater than 3/4.


You could also complete the square.
x^2 + x + 1 = x^2 + x + 1/4 + 3/4
= (x+1/2)^2 + 3/4.
Since the first term can't be negative, the obvious minimum is 3/4, when x=-1/2.

mechanics help

you drop a rock, 7.8s later you hear echo. speed of sound at 330m/s, how far did the rock fall?

whats the method for tackling these kinds of problems? im given acceleration and init velocity of two objects, and asked to find time values permitting both functions to travel the same distance
so you get two position functions, one in terms of acceleration and time, the other in terms of velocity and time. but when i set both the sound and the rock equal to displacement, and then substitute displacement setting the equations equal, i get a time value that isnt within the range of the given time.

similarly, if i graph these two functions and find their intercepts, the intercept, 67, doesnt make sense to me. two lines, a position from a constant acceleration, and a linear posiiton in terms of a constant v. there is a ratio between the growth of the two functions, but plugging and chugging through kinematics equations isnt clicking

i tried subbing displacement, and then setting that quadratic to 0, and finding those roots, but theyre also not within the allowed time range.

i could plug and chug values, but i know there is a technique for approaching this type of problem, i just cant find it

>>12051220
undergrad? master's? doctorate?
if you know some programming and know how to apply the math to business analytics, you can reasonably get $40-60k starting out, up to $80-90k after a few years. similar with master's. Not really sure that the extra cost is worth it but it will open some doors to higher paying jobs if you have additional skills.
PhD? I don't really think it's worth it to try to teach period but you can get good money in the private sector if you hustle

my electronics lecturer explained to the class why wires have a higher resistance when conducting higher frequencies. however, his explanation was unfortunately completely unintelligible. can a kind anon here please give it a try?

>>12052227
write it as a math problem
the time it took to hear the echo is equal to the time it took to fall plus the time it took for the sound wave to reach you
[eqn]7.8 = \sqrt{\frac{d}{\frac{1}{2}9.81}} + 330d[/eqn]
(im phone posting i pray the tex came out okay)

>>12052771
oops, second term should be
[eqn]\frac{d}{330}[/eqn]

I took all the pure math in the first 2 years of college and proceeded to take all the CS/computational classes for my minors the rest 2 years. I have my last exam period coming up and I have to take a real analysis exam I left behind. I literally have to pause and think for examples on topological results on every damn definition. I forgot everything. Fuck.

I'm new.

Tower of hanoi, blah blah prove that it takes 2^n - 1 moves.
I understand all the steps of this proof, but its not quite evident to me why...

1. assuming the solution for n discs takes 2^n - 1 moves, and then
2. showing that the solution for n+1 discs takes 2^(n+1) - 1 moves

...along with the base case n=1, sufficiently proves this. I mean I kind of see it but how do we know we couldn't have assumed some other expression other than 2^n - 1 and then found a similar result for that?

Thank you

>>12053601
m(1) = 1
m(k+1) = m(k)+m(1)+m(k) = 2*m(k)+1

m(k)=2^k-1 is the only function which satisfies both conditions.

>>12053650
Thank you, but thats the exact bit I'm not quite getting, and maybe it a bit daft but...
How do we KNOW thats the only function which satisfies both conditions? ie how do we know another function may not also satisfy both?

I feel like im missing something stupid..

how do humans have some sort of 'sense' that exists outside themselves, being able to tell when people are watching you even though you can't see/hear them, becoming on edge when entering a dangerous situation even though you're not consciously aware of it shit like that

>>12053743
They don't, schizo.

>>12053827
people feeling on edge around psychopaths is an observed scientific phenomenon, so is "goosebumps" happening when a persons observed without knowing they're observed - why reply to me if you don't care about science

>>12053832
>Source: My ass
As a professional gangstalker I can assure you that they don't

where the fuck is sci torrent

>>12053832
you should literally take your meds or change the prescription because they're not working

Is there a way to solve (c) that my 90 IQ brain can understand?

>>12053864
call a^5 b, a^5 is now b and a^10 is b^2, now you have a quadratic, replace b with a^5 when you are finished factoring

>>12052751
current doesnt flow through the whole wire but moves more and more towards the outer part as frequency increases
loop up skin effect

I’m leaving my job to go work elsewhere, so i figured now is the time to steal some heating plates and glassware to set up a home laboratory. Only i havent really thought this through and i dont really know what i need or what i’m even going to use the lab for.

Anyone got experience doing chemistry at home for fun or for more practical purposes? Not making explosives or drugs.

>>12052227
did ya figure it out?

why the fuck is circuit theory so fucking GAY

using the taylor series including the third exponent about x0=0, calculate the approximate value of
[math]\int_0^3\frac{sin(x/3)}{x} dx[/math]

how do i do this, i divide by 0 if x=0

>>12054499
lim x -> 0 sinx/x = 1

>>12053659
Every value of m(k) is determined by those two. m(1)=1 => m(2)=2*1+1=3 => m(3)=2*3+1=7 => m(4)=2*7+1=15 => ... ad infinitum. IOW, there's only one function m(); there may be different ways of writing it, but they're all equal.

>>12054499
Find the Taylor series for sin(x/3), divide by x. The Taylor series for sin(x/3) doesn't have a constant term so all terms have x in the numerator.

in pic related, are the points referring to (c_1, c_2), so my system of equations would be:
[math]y = 1(c_1)x + 0c_2[/math], etc or are my points of the form (x,y), so my system of eq'ns would be:

[math] (1c_1)x_1 + c_2 = 0\\ (2c_1)x_1 + c_2 = 0 \\ (4c_1)x_1 + c_2 = 0 \\ (5c_1)x_1 + c_2 = 3[/math]
And so our matrix equation Ax = b is:
[math]\begin{bmatrix}1 & 1 & 0 \\ 2 & 1 & 0 \\4 & 1 & 0 \\5 & 1 & 3 \end{bmatrix}\begin{bmatrix} c_1 \\ c_2 \end{bmatrix} = b[/math]

We see it is inconsistent because we can reduce the final row to 0 0 3.

Did I set up the matrix properly here?

>>12032464
what can science do about my gross veiny hands at 21 y.o.

>>12054690
I would interprete them as (x,y)

Also, did I set up thismigration matrix properly?
\begin{bmatrx}
98.71 & 0.27 \\
1.29 & 99.73
\end{bmatrix}

>>12054725
[math]
\begin{bmatrx}
98.71 & 0.27 \\
1.29 & 99.73
\end{bmatrix}
[/math]

>>12054710
so then my eqn's are:
[math]
c_1(1) + c_2 = 0 \\
c_1(2) + c_2 = 1 \\
c_1(4) + c_2 = 2 \\
c_1(5) + c_2 = 3
[/math]

And my matrix is just the the vectors containing the x-values and y-values?

>>12054732
I never done anything like this, but
0.9871 & 0.0129
0.027 & 0.973
would be my guess

>>12054748
How do matrizes work here btw?
x & 1
2x & 1
4x & 1
5x & 1
and b is (0,1,2,3)

>>12054329
Yes tyvm
245m
Feels good man v=d/t

>>12054856
good job anon :)

>>12032464
This is severely retarded, but say you have -x^2 and you plugged in a 2. Would that be -2^2=4 or -(2)^2=-4?

>>12049843
Can someone link a video with a less autistic way to do this?

>>12054949
generally speaking, exponents have a higher order of operation than negative signs (which can be thought of as multiplication, since youre just multiplying by -1). so: [eqn]-2^2=-4\\(-2)^2=4[/eqn]

>>12054951
No
3rd and 4th grade polynomials only have autistic solutions
Just use numerics

>>12054952
Thank you, couldn’t find a clear answer anywhere.

>>12054615
Ok, think im just overthinking it, thank you!

>>12032464
Are there any timesaves for graphing ax^2+bx+c parabolas? Perhaps a way to eyeball the vertex or something?

Is it possible???

>>12054996
the vertex is always at [math]x=-\frac{b}{2a}[/math]. you can then plug that x into the equation to get the y value of the vertex

>>12054998
yes

>>12055008
Forgot about this, thanks

>>12055011
Sick thanks

Why the fuck can't i find a copy of Lombardo's translation of The Theogony online, but other translations are easy to find

>>12053868
Thanks

i^3 written in a+bi form is 2i.
can someone tell me how? I'm stuck. :(

>>12055213
i^3 is -i, not 2i

>>12054782
>(me)
ye

>>12055233
ok thanks, my textbook can suck my dick

>>12032464
This post may have been meant for this thread.
>>12055276

>>12055316
Wolframalpha says (0.7,-0.6)
Looks alright on geogebra

I'm having trouble finding the steady state vector here. Does this look right?
[eqn]
\begin{bmatrix}.9871 & 0.0027 \\ 0.0129 & 0.9973\end{bmatrix} \begin{bmatrix} x_1 \\ x_2 \end{bmatrix} = \begin{bmatrix} x_1 \\ x_2 \end{bmatrix} \\
0.9871(x_1) + 0.0027(x_2) = x_1 \rightarrow 0.0027(x_2) = x_1 - 0.9871(x_1) = 0.0129x_1\\
0.0129(x_1) + 0.9973(x_2) = x_2 \rightarrow 0.0129(x_1) = x_2 -0.9973(x_2) = 0.0027x_2
[/eqn]

Am I on the right path here?

>>12055339
Sorry I deleted because I found my error soon after, I was forgetting to row reduce the other side of the equation simultaneously so my results were wonky. But I utlimately arrived at the same answer, thanks for checking.

>>12055488
Yes, just go on and check the answer

>>12055531
wdym go on and check the answer? how?

>>12055531
ok, got x=-34/9, y=43/9. gonna check if it's right now

>>12055544
multiplying the matrix with your answer
It's steady state, so check if Ax=x

>>12055578
phpew, calculator mistake, i got it now thanks!>>12055531

>>12055581
Ok, so I'm supposed find the long term behavior of this markov process, and I've found my steady state vector. How do I show the long term values other than ,multiplying by large numbers? It reads like a limit problem, but I don't think that's the move.

>>12055581
oh wait the answer to the long temr values is jsut the vector I found innit

>>12055637
Yes, it's a fixed point

>>12054748
[eqn]
\begin{pmatrix} 1 && 1 \\ 2 && 1 \\ 4 && 1 \\ 5 && 1 \end{pmatrix}
\begin{pmatrix} c1 \\ c2 \end{pmatrix}
=
\begin{pmatrix} 0 \\ 1 \\ 2 \\ 3 \end{pmatrix}
[/eqn]

For maximum flux density in a coil, is current or number of turns more relevant? Is there a formula somewhere expressing the relationship? Making a coilgun and google refuses to give me straight answer on this

>>12056322
Nvm found it. permeability*turns*current / coil length

So I'm about to transfer from community college to university as math/cs major, and I want to take the right classes. I'd like to take a lot of the upper division math stuff like real analysis, abstract algebra, topology, but there just isn't enough room in the degree, given that they all require sets of prereqs.

My question is, how do I convince profs to let me cut the prereqs, and take the stuff I'm really interested in? I don't want to graduate w/o having taken abstract algebra, for example, but don't want to take any more classes than required either. Hopefully you get the jist of what I'm trying to say.