/sqt/ stupid questions thread

the instructions only told me to find the second derivative

Implicit differentiation is pointless when y can be solved for explicitly.

How many points was this worth?

You didn't prove [math]x\ \neq\ 0[/math] before dividing by it and that [math]y[/math] was of class [math]\mathscr D^2[/math]. Also, you should write [math]y\left(x\right)[/math]. A function isn't a number.

10, my professor is an engineer

Your professor is a retard for designing a question with a much simpler solution than whatever he expects you to do

You are an autist boy.

No, I just did two years of math in a civilized college.

I did last time and got marked wrong because my solution was different from my professor's

pic unrelated

Attached: 1521802600221955309880.jpg (1968x2624, 1.06M)

I know it's extra-stupid, but could I get an answer to this: ?

Is it because alcohol takes energy to metabolize? Do the active compounds in cannabis not require as much energy to process? What gives?

ask the person that market it brainlet.
Oh right, you're probably too much of an autist to think about making conversation with another person.

Hey people of /sqt/, I'm just curious on whats the best way to use khan academy?
As in should I go though math by subject or math by grade?

Hey guys I'm a real brainlet when it comes to maths and am having some trouble trying to solve this problem I have. I want to find the coordinates of B and D in pic related. I have the coordinates of A and C currently and have calculated the length of each edge and the diagonal length.

The problem is it's a 3 dimensional object and it's on a reasonable angle such that A is much deeper than C.

If anyone could point me in the right direction of what they'd do next that would be super appreciated.

Attached: B0Cw3UX.png (1280x988, 1.47M)

I know this is a very easy question but I don't know much math so I don't know where to look this up.

Anyways let's say you have a deck of cards with an N amount of cards in total. There are only two types of cards: R red and black.
You shuffle the deck and draw 3 cards in a row.

What are the odds of drawing 0, 1, 2 or 3 red cards? How would the formula look like with the variables N (number of cards in the deck) and R (number of red cards in the deck)?

Attached: 3_playing_cards.jpg (1600x1067, 108K)

I am supposed to calculate the angle of deflection for a proton crossing the magnetic field of a dipol magnet. The proton is moving perpendicular to the magnetic field. The formula for the angle [\latex] $\alpha$ [\latex] is given by [latex] sin(\alpha )=L/R [\latex] what happens if my radius is smaller than the lenght L of my dipol ?

Attached: field.png (304x254, 29K)

R choose 0/N choose 3
R choose 1/N choose 3
R choose 2/N choose 3
R choose 3/N choose 3

Best place to download free scholarly articles/material?

if my unit vector ends up being 1.019, have I fucked up? Should it always be exactly equal to one?

I ended up getting:
sqrt(-9.7631/26.5998 + -26.052/26.5998 + 8.15321/26.5998)
= 1.019

i thought unit vector was (1/||v||) * v

Is it theoretically possible to engineer an electrical mechanical master key/device to magnetically unlock any common house lock?

I do:
vi/||v|| + vj||v|| + vk||v||
Not sure if that's the same as you said.

Keep your limit notation until the point where you substitute in the variable.

vi/||v|| + vj/||v|| + vk/||v||
Those have all been over the magnitude, miss typed that.

but lim as x->c of f(x) =/= f(x)

Exactly, that's why you need to keep your limit notation in there.

I did, I was chewed out for declaring f(x)

he didn't even define dy/dx in his solution baka

baka

s.m.h.

anyone?

It's theoretically possible but practically impossible, you'd still need to know the configuration of the pins to unlock it. You can use some kind of magnetic inductor to melt the lock if you want

Why not just pick it?

How do I calculate the vector of two points on a cube?

Have a device do it for you

question doesn't make sense

Isn't a vector a line/direction in space? So I want to calculate the vector that is between two points on a cube

Pythagorean theorem?

depends on which point is the origin

AC is just point C - point A, right?

only if A and C line up horizontally and C > A

How do you work it out if they don't line up horizontally? C is > A in this situation.

AC = sqrt(A^2 + C^2)

How old are you?

What is the deal with women who take math/engineering classes?

Probably older than you.
Comp sci student with one subject left, my first years maths class that i've been putting off forever because I hate maths. I understand the beauty of maths but I really struggle with it and thus completely loathe it.

Let [math]\epsilon>0[/math]. How do I prove that the set [math]\{ x\in [0,1] : f(x)\geq \frac{\epsilon}{2} \} [/math] is finite, for [math]f(x)[/math] being Thomae's function?

by the way it's called the distance between points, not vector

I don't want the distance between the points though. I've already calculated that. I want the vector that is the center of two points.

Where I've circled in this picture. Because I want to rotate it 90 degrees right and left to get the location of B and D

Attached: asdasd.png (1274x988, 1.46M)

the center's coordinates O(x_0,y_0) are (|x_a-x_c|/2, y_a - |y_c|/2)

I should have said the center to point A. Center (C) being: {37.62465, 21.677315, 12.501505} which is what you were saying, which isn't the vector CA

(x_c + |x_a-x_c|/2, y_c + |y_a - y_c|/2)*

Yes I have the coordinates, I want the vector of Center -> A so that I can rotate it 90 degrees either way and get the coordinates of B and D which are at Z index: 12.501505

This can't be right because the X coordinate it gives is less than the X coordinate of C

If you have the coordinates of the center C and any of the vertices, for example A, then coordinates of the vector from C to A are just the coordinates of A-C. You can rotate this and then add it to C to get the coordinates of the other vertices.

Attached: square.png (1274x988, 2.48M)

A straight direction down is not equal to it's diagonal direction.

you're trying to get the location of B and D right?
D's x coordinate is the x coordinate of C + short side + long side, its y coordinate is y coordinate of C + long side

B's x coordinate is the x coordinate of C + long side - short side, its y coordinate is y coordinate of C + long side + short side

D's x coordinate is the x coordinate of C + short side + long side, its y coordinate is y coordinate of C + long side - short side*

Why the hell do people in major in Mathematics education? Is it literally because they're too dumb to major in Math? What's the benefit of majoring in the former. Can't you still land a teaching job with a math degree?

so long side is Yo - Yc?

Wouldn't the correct way to do this be to get the vertice that is center to A and then rotate it either direction to determine B and D?

no, that would be the retarded way

newX = centerX + (point2x-centerX)*Math.cos(x) - (point2y-centerY)*Math.sin(x);

newY = centerY + (point2x-centerX)*Math.sin(x) + (point2y-centerY)*Math.cos(x);

I already have the Z coordinate. This is the right way.

What you've done I can't prove to be true.

Does anyone know if its possible to use k-means clustering to identify confounding groups (like the ones in the graph) for regression analysis?

(accidentally posted this in the previous thread)

Attached: confounding groups.png (653x653, 7K)

I hate picking symbols

Let:
ö := the distance between any vertex of the square and the center
s := the length of the sides of the square

Prove that D(x_d,y_d), x_d = x_c + r + p and y_d = y_c + r - p (what I just said in my previous post)

(r + p)^2 + (r - p)^2 = s^2 and r^2 + p^2 = ö^2 implies that for D(x_d,y_d), x_d = x_c + r + p and y_d = y_c + r - p

s^2 = 2ö^2
(r + p)^2 + (r - p)^2 = 2r^2 +2 p^2
r^2 +(2rp) + p^2 + r^2 -(2rp) + p^2 = 2r^2 +2 p^2
r^2 + p^2 + r^2 + p^2 = 2r^2 +2 p^2
2r^2 +2 p^2 = 2r^2 +2 p^2

∴D(x_d,y_d), x_d = x_c + r + p and y_d = y_c + r - p

q.e.f.d

Attached: square.png (1274x988, 2.48M)

I forgot to include that the vertical distance from D to O is equal to the horizontal distance from C to O and that the horizontal distance from O to D is equal to the vertical distance from C to O

actually, nevermind

>A straight direction down is not equal to it's diagonal direction.
No it is not but you can use rule of triangle and find CO via two other vectors

what are you trying to find even?

Is the sum of all points a given distance from a central point equal to infinity?

well there are uncountably many points being summed in that "series", none of which approaches 0, so...

How do you pronounce [math] \LaTeX [/math]?

>didn't prove x!= 0
x is a variable, every point at which it is well defined it is also differentiable, no problem
you're second point is beyond the scope of the question
while its true that he should express y as a function it's beyond the scope of the question.
abuse of notation aside he didn't exactly do anything wrong.

the lines without the limit notation aren't directly following from the above lines, he's declaring f(x), working with it to reduce then substituting it back into the original equation.
the only thing you did wrong was forget the 1 in the limit, but you should probably make it clear by writing "consider:" before declaring f(x) or something

Lah-tekh

just say layteks and listen to the autists ree

Isn't this an integral over a surface?

reasoning for why the soil of a plant i've been growing (for a project) contracted a saprophytic fungi? this particular plant was also grown with a .15% NaCl watering solution

If you have a time varying magnetic field, does this mean that a paritcle of charge q will be pulled in one direction for time t before the magnetic field switches?

lateh

What would be the most documentable, reliable and fair way to conduct a prize draw within a sample of ~2000 survey respondents? One respondent will receive a prize.

Anything in R? I already found one solution but decided to ask here anyway.

of course we have random.org but meh

Yes. Conisder it as a sin wave.

How the FUCK do I do this?
My stat mech professor just yanked the value of this out of his ass. It's (pi^2)/3, but I don't know how to get that.

Attached: integral.gif (107x45, 748)

Trig substitution.

integral-calculator.com/

I've got a weird question - do you have any assigned textbooks or do your teachers/professors just recommend a couple books and expect you to go through all of them? mine usually recommend around 8-10 books each and I'm not sure how I'm supposed to go through all of this simultaneously

Most people don't read them. Take a look at perhaps 2 of them, the ones you think will be most helpful

Trying with hyperbolics but there seems to be some weird divergences in the integration by parts which is odd because the integral is definitely convergent; it's doubly exponential in the denominator

Is pineapple a good pizza topping?

If kernel density estimation is supposed to help you figure out the distribution of a dataset without making any assumptions as to what the true distribution actually is, doesn't choosing a kernel function kind of render that moot? Won't the choice of kernel function affect how the overall estimated distribution comes out?

Attached: image.png (500x250, 22K)

that's what I've been doing so far but I can't help but wonder if the professors actually expect me to read them all back to back or just pick a couple and supplement with some additional information from others

You didn't define the metric space.

Wait nevermind, it was an error. It can be done easily by the gamma function.