STUPID QUESTIONS THREAD

>STUPID QUESTIONS THREAD

I'll start

so I'm supposed to find the area between two functions

y1=ln2x, y2=lnx, and x=2

ln2x is the upper function and lnx the under? function, I did it, and I get

2ln2-1/2, but the book's result is 2ln2 only

I ran it through wolfram alpha and I get 2ln2-1/2

what gives? did I formulate the problem wrong?

integral of y1 - integral of y2 = area between curves

Other urls found in this thread:

hyperphysics.phy-astr.gsu.edu/hbase/thermo/adiab.html
twitter.com/SFWRedditImages

ln(2x)-ln(x) = ln2

the integral from 0 to 2 of ln 2 is 2ln2

aaaaaaaaaha, for some reason I was considering the area only above the x-axis

thanks a lot, user

Okay cool.
I'm having trouble getting the right answer for this. I'm taking cosine law, deriving it and putting it into the work energy equation but my answer is not what it should be. Am I doing it the right way.

So, I've been given pic related as a task, but I'm confused since it seems that all I'm doing is squaring and summing elements of a white noise vector, which is independent of m. The question says to do it for 2 values of m, but they're (from how I'm reading it) both going to give the same answer anyway.

I don't know whether the question is so supposed to reduce to something stupid like this or whether I'm, well, being stupid instead.

How the FUCK does light have momentum but not mass

how does this work? why are there 2 e states? why not just write a single e state then fork out with either a or b

aa* | bb* = {a,b,aa,bb,aa..., bb...} right?

>doesn't know about dark mass

are you memeing me or does it explain the problem

use the lagrangian

Can a molecule be a stereoisomer and enantiomer at the same time?

How did they find the value for pi

meme

they divided circumpherence by diameter

what should i do next

Yeah
Enantiomer is a type of stereoisomer. As are diastereomers, and meso compounds.

>and meso compounds
ehh actually probably not, since mesos are basically the same thing

>gief mesos plox

Retard here, question is in pic related.

Im just not sure of the technique to pick to minimize all values, im sure its related to derivation but I dont remember how to minimize the ENTIRE graph, only how to find mins and maxes of that graph. Been 3.5 years since ive touched calculus so be gentle pls.

well first you find all values of p where the derivative is 0
(every min or max will have derivative = 0, but not every point where derivative is 0 will be a local min or max)
then just look at each point individually on the graph of the function. there won't be too many of them.

although in this case it looks like you're just trying to minimize [math]\frac{\frac{1}{p}}{ln\frac{1}{p}}[/math]
you can look at a graph of the function and see that it asymptotically approaches [math]-\infty[/math] as p approaches 1 from the positive direction

Interesting problem, user. What answer are you supposed to get?

If the answer I have matches what is correct, then I'll take you through it, but I am not 100% convinced that my approach is correct.

Would love to hear Veeky Forums's opinion on this: How old is too old for grad school?

What's the difference between SEM and factor analysis?

Is the mount hood volcano in Oregon literally all basalt rock? Is there a history of the layers like say the grand canyon? I know that is a crazy comparison but one should get the point. Surely, there has to be something out there describing the history of the layers before it formed into what is it today or is volcano formation simply another situation entirely?

I think the oldest new student in our department is early thirties.

Really, never, if you just want to learn, but if your past forty, it's going to take you at least five years to get the degree, and it may be tough finding a job when you get out and are approaching/over fifty.

I'm 24, currently working full-time as an engineering tech and pursuing a bachelor's in Applied Math part time. I expect to graduate in about 3 years, but who knows what can happen in a lifetime? Really interested in studying CFDs and generally scientific computing. Thanks for your input, anyways.

>why are there 2 e states?
It could be to make it more noticable that it's supposed to branch into a's and b's. So it's not actually necessary, but it's just like that to make it more visually stimulating.
It could also be to emphasize the difference between a deterministic and a non-deterministic finite automaton. In a deterministic one, you are only allowed to have one transition per symbol and state. So in this case, you would only be allowed one ε transition from state 0. (or maybe even none. it's not very normal to have a ε transition. we never did that in my automaton class). Then there are also deterministic complete automata, where you need to have one transition for every symbol from your alphabet, for every state. pic related
>why not just write a single e state then fork out with either a or b
You can do that. In fact, you can just leave out state 1 and 3 entirely, because nothing is gained from having them, because ε (greek e) is the empty word. pic related
>aa* | bb* = {a,b,aa,bb,aa..., bb...} right?
Yes. You can use brackets to make it more obvious. ( (a) ((a)*) ) || ( (b) ((b)*) )

I'm thirty in my Junior year. Admittedly, it does feel shitty but no one really bothers you about but I guess my looks help? My first year, someone thought I was a dual enrollment student in HS. kek. I see people older than me going for their first degree as well so that helped my confidence somewhat. 3.8 GPA at the moment.

Thank you! Ill mess with this a bit more, I knew this wasnt difficult I just had a bit of a brain fart I guess.

When you pump a bike tire up, the pressure and volume of it changes, therefore temperature should remain constant, but the surface of the tire feels warmer after. What causes this?

a friend of my dad's went to med school in his late 40s and now works at NIH

>pressure and volume of it changes, therefore temperature should remain constant
where'd you get that idea from user
P, V n, and T are all related to each other. Just because P and V are changing doesn't mean T can't change as well, as long as the math works out and the whole equation remains constant.

And in this case n is increasing as well. You're adding more air to the tire.

Real quick question. I haven't ever taken a combinatorics class, but I know that it exists, so I know a littler jargon.

So, I've got 4 slots, and each slot has the possibility of holding 1 of 3 balls. Two balls can't fit in one slot, and all the slots are filled with at least something. Assuming that reading the slots off in a row produces a sequence, how many different combinations are there EXCLUDING duplicates.

So, if the choice of balls were blue, red, and yellow, you could have R, Y, Y, B.

when using a steam table, you can just do h = h'' - h' to find out how much enthalpy was used to make steam out of water at a fixed temp/pressure, does this work backwards? like is the same enthalpy 'used'/created to condensate water as vaporizing water (at the same fixed temp/pressure) ?

There's no need for any epsilon moves; you could just fork from the start state.

But it's much easier to algorithmically construct a NFA from a RE if you allow epsilon moves.

E.g. to compile the | operator, you might construct the NFA for each branch with distinct start states, then add an epsilon move from the parent start state to the start state for each branch.

That way, the overall NFA will be correct even if the child NFAs loop back to their start states.

fuck im dumb

of course it is

Must all colours appear (at least once), or is YYYY allowed?

I count 15 (it's easiest just to generate them, rather than worry about an algorithm).

RRRR
BBBB
YYYY

RRRB
RRRY
BBBR
BBBY
YYYR
YYYB

RRBB
RRBY
RRYY
BBRY
BBYY
YYRB

I am struggling with part B of exercise 3.3.6

Any ideas? My only coherent thought has been that because the cantor set is compact, there exist a convergent subsequence of both Xn and Yn that converges to a number inside the cantor set. But then I don't know how that helps me.

Is that something? Does it ring any bells?

Wait wait wait. My IQ just increases by 5 points.

As I can pick a convergent subsequence of Xn, I choose an arbitrary one. Call it XXn

Then I pick the subsequence of Yn such that it contains the same 'steps' as XXn and call that subsequence YYn

As these sequences have the property that
1) XXn converges to x
2) At every step n, xn + yn = s

I can prove that YYn converges to s - xn

Is this something?

This is the correct idea. The only thing left for you to do is to prove that x and y (the limits of xn and yn = s -xn) are both in C.

Hint: All C_n are closed.

NO NO wait. I have seen the light. My IQ is oficially unbounded.

I can pick a subsequence of Xn that converges all cait X2n and then construct a subsequence of Yn such that it contains the same steps, call it Y2n.

Them pick a subsequence of Y2n such that it converges and call it Y3n. Then construct the subsequence of X2n that contains the same steps, call it X3n

Then X3n converges too because it is the subsequence of a convergent sequence!

And then, as X3n and Y3n are sequences defined in a compact set, they converge to a point in the cantor set.

Now, say X3n converges to x and Y3n to y.

In each step, xn + yn = s so now

lim(X3n + Y3n) = s
but also
(lim X3n + Y3n) = lim(X3n) + lim(Y3n) = x + y

So then we conclude x + y = s

Thank you guys.

I think I am correct but if some topologists or Analysts can check my proof I'd appreciate it.

>And then, as X3n and Y3n are sequences defined in a compact set, they converge to a point in the cantor set.
This line seems very glossed over considering there's at least a couple of lines worth of reasoning you need to establish that the limit of xn is actually in C. Just saying "compactness" is not enough. What compact set are the sequences defined in? How does that allow you to claim the limit is in C? (compactness only talks about the set the sequence is in, and the entire sequence is quite likely not in C).

Everything else is correct but there's enough of a chunk missing there that you'd lose a mark or two at least on a test.

Fuck man I am a fucking brainlet after all.

My next idea would be to go even deeper with an X4n that contains only the points in X3n such that xn is in a boundary of the closet sets that make up C.

I know there are infinitely many of this, because of the way I defined my Xn for part 1.

Then this X4n converges to a point in C (as it is a sequence defined entirely in C)

But then as it is a subsequence of X3n, it converges to x! So x is in C

Then I can do the same to prove y is on C.

Is this it Papa? Do I get a Fields Medal now? I don't want to be a brainlet.

From my own understanding, information that is being transferred must exist in its entirety in the transmitter and again in total, or greater in the case of redundancies, in the combination of the transmission and the receiver.

In a similair vein, you cannot impart or glean information without gleaning or imparting it.

This draws strange parallels to energy conservation rules to me, is infirmation a conserved quantity?

is this stuff in a graph theory books? where do i read about this stuff

good books on compilers??

What does resection mean? How is it different from amputation? Any medfags who can answer because google isn't helping.

please elaborate on your definition of a duplicate

does anyone know the lecture series that outlines that there are repeating numerical results to equations in the universe?

it also talked about some geometry shapes, number theory and all that fun stuff.

it was a full lecture series and it was presented by an older gentleman

is there a way to describe a parabola using trygonometric or hyperbolic functions?

Is there a fundamental definition for length, area, and volume?

Let [math] m \in \mathbb { Z } ^{+} [/math]. Let [math] M [/math] be a smooth manifold with [math] p \in M [/math] and [math] \left ( U, \phi \right ) [/math] a smooth chart with [math] \phi ( p ) = 0 [/math]. Show that [math] X_i : C^{ \infty } (M) \to \mathbb { R } [/math] defined by: [eqn] \forall f \in C^{ \infty } ( M ): \hspace { 3 cm } X_i f = \left ( \frac { \partial } { \partial x^i } \left ( f \circ \phi ^{-1} |_{ \phi (U) } \right ) \right ) (0) [/eqn] Show that [math] X [/math] is a tangent vector at [math] p [/math]

The fact that it's a map from [math] C^{ \infty } (M) \to \mathbb { R } [/math] follows from it's definition, likewise the fact it's linear follows since derivatives are linear. So all that remains is to show it satisfies Leibniz rule, let [math] g [/math] be another function defined as above, then [eqn] X(fg) = \frac { \partial } { \partial x } \left [ \left ( f \circ \phi ^{-1} \right ) \cdot \left ( g \circ \phi ^{-1} \right) \right ] \text { but f,g,} \phi \text { are just smooth functions, so we can just employ the chain and product rules} \\ \hspace {1.3cm} = \left [ \left ( f' \circ \phi ^{-1} \right ) \phi ' ^{-1} \right ] \cdot \left [ f \circ \phi ^{-1} \right ] + \left [ f \circ \phi ^{-1} \right ] \cdot \left [ \left ( g' \circ \phi ^{-1} \right ) \phi ' ^{-1} \right ] \\ \hspace { 1.3 cm }= X(f)g + fX(g) [/eqn] Which is precisely Leibniz rule.

Does that look alright to everyone else?

what was the point of m in Z^+?

Just to show that M was m-dimensional, I didn't realize that I'd cut that out.

I cant figure out this question, and I cant find it anywhere!:
Solve sin(a) = sin(b), or cos(a) = cos(b) , where a and b are linear functions.

Any help would greatly be appreciated! :D

For example, solve:
sin(x+2) = sin(3x-5)

Amputation refers specifically to removal of a limb. Resection is more general; it refers to removal of some "part" (e.g. an organ, or a specific portion such as a lobe) in its entirety..

Basically, if the tissue to be removed is defined by an anatomical boundary (i.e. it's a part that has its own name), it's a resection. If it's "whatever tissue is infected / damaged / needs to be removed", it's an excision.

> is there a way to describe a parabola using trygonometric or hyperbolic functions?
Algebraically, a parabola is just y=x^2, or an affine transformation of that.

Geometrically, it's the set of points whose distance to a point (the focus) is equal to the distance to a line (the directrix).

sin(x)=sin(y) if x=y, or y=x+2nπ for integer n (periodicity), or y=π-x (symmetry about π/2), or y=(2n+1)π-x for integer n (corollary of periodicity and symmetry).

cos(x)=cos(y) if x=y, or y=x+2nπ for integer n (periodicity), or y=-x (symmetry about 0), or y=2nπ-x for integer n (corollary of periodicity and symmetry).

In each case, the first and third equations are just specialisations of the second and fourth. So sin(f(x))=sin(g(x)) gives you two equations involving f(x), g(x) and integer n, each of which has infinitely many solutions (one for each n).

E.g.
sin(x+2) = sin(3x-5)
=> x+2 = 2nπ + 3x-5 or x+2 = (2n+1)π-(3x-5)
x+2 = 2nπ + 3x-5 => 2x=2nπ+7 => x=nπ+7/2
x+2 = (2n+1)π-(3x-5) => 4x = (2n+1)π+3 => x=(n/2+1/4)π+3/4

More generally:
sin(ax+b) = sin(cx+d)
=> ax+b = 2nπ + cx+d or ax+b = (2n+1)π-(cx+d)
ax+b = 2nπ + cx+d => (a-c)x+(b-d) = 2nπ => x=(2nπ+d-b)/(a-c)
ax+b = (2n+1)π-(cx+d) => (a+c)x+(b+d)=(2n+1)π => x=((2n+1)π-b-d)/(a+c)

Thanks man!

Should I choose Electrical & Electronics Engineering or Computer Engineering?

in pic related, how does the poster change the upper limit from a = pi/2?

it literally says the substitution right before they do it

How do I know if I'm too unintelligent to learn programming? I've made progress but I feel like I'm failing to grasp some
concepts at all. Nested loops and recursive functions in particular give me a headache. Im having so much trouble with Python, an easy language, I wonder how I can ever expect to move on to other languages.

Know your math.

I know it _says_ so right there, m8, what I wonder is how does he go from a to pi/2? the reasoning behind it?

is it because the ellipse equation itself is =1, subsequently -1

sin u = x/a

if x=0 then sin u = 0 => u= 0
if x=a then sin u=1 => u=pi/2

fuck I'm a moron, thanks guy

I think my professor just gave me some bullshit that doesn't make any sense. Any Physics majors out there wanna tell me this shit makes sense. The answer is in bold. for the velocity to be constant the accel has to be 0 right.

>I think my professor just gave me some bullshit that doesn't make any sense.
>blaming your own stupidity on someone else
I hate your kind. This is high school physics.

then solve it, and prove that this problem isnt borked

if evolution is real then how come monkeys still exist???

check mate atheists

your right im blaming myself.

>for the velocity to be constant the accel has to be 0 right
Yes, which just means that the friction has to exactly balance out the force due to gravity.

Do you think having an acceleration of 0 means something can't be moving?
That's a surprisingly common misconception for how dumb it is.

>for the velocity to be constant the accel has to be 0 right
never said that have no acceleration would mean that something isn't moving. lrn to read

If adam and eve were real then why are there niggers?

That is one of the biggest mysteries of evolutionary science

Well then why do you think it's bullshit that doesn't make any sense?

look at the weight differences. there is no way a 10 kg block will slide down a slope connected to a another block 5 times in weight

oh yeah
that's likely a simple editing mistake. somebody was copy-pasting problems and changing numbers around and forgot to verify that the whole thing made sense

you can probably safely assume that it's moving up the slope instead

I posted this formula in your other thread:
u=(Msin(theta)-m)/(Mcos(theta)). Since as you pointed out the block moves up the slope rather than down it, the friction force points down the slope. The new formula should be:
u=(m-Msin(theta))/(Mcos(theta))

I was plugging in the values, and I accidentally put did (10-10sin(30))/54cos(30) and got .1 so your professor must have plugged in two numbers wrong and used the wrong formula. Sorry but your school sucks

My brain feels stuffed with wool today. I'm a Calc I student learning inverse function and logarithm differentiation blanking on why (d/dx)(xln(a))=ln(a). The full problem so far is (d/dx)(a^x)=(e^(xln(a)))*(d/dx)(xln(a)) and I get that, but I just keep thinking in circles that the right side is just (a^x)*(1/a^x)*(da/dx).

ty i really appreciate your post.
my proffesor has parkinsons and dementia but has tenor so this is probably why he can write shit.

>u=(Msin(theta)-m)/(Mcos(theta))

Shouldn't that be [eqn] \mu = \frac { M \sin \left ( \theta \right ) - m \cos \left ( \theta \right ) } { M \cos \left ( \theta \right ) } [/eqn]

Since the normal force is at an incline.

>why (d/dx)(xln(a))=ln(a)
ln(a) is just a real number. Or am I missing something?

No, I got the formula from setting the force on the small block equal to the force on the large block:
Mgsin(theta)-uMgcos(theta)=mg

if it's moving up the slope it's Mgsin(theta)+uMgcos(theta)=mg

Oh, I'd inserted an additional cos(x) for some reason.

No, you're absolutely right. It as trivial as I was sure it had to be, fuck this sleeping four hours a night for two weeks garbage, never again. Thank you user.

No problem, I had worse fuck ups.

Help a megabrainlet out:
What is BD and CD?

google law of cosins

Angles ABC and CBD are supplementary, so CBD=180-100=80, and BCD=180-80-90=10.

You know the length of BC, so use the Law of Sines for the others.

helo how to solve this

...

In a mechanics problem, a particle is accelerating with constant power [math]P[/math] from [math]v_0[/math] to [math]v[/math].
Trying to work out an expression for power, in order to find out time needed to accelerate:
[eqn]
W=Fx \implies \dot W = \dot F x + F \dot x
\implies P = \dot F x + Fv
[/eqn].
I don't know how to make sense of this, as F is a function of v (I think?) Is this a second-order ODE? Textbook explainations seem to ignore the possibility of varying F and just give P=Fv.

hey im going to keep this thread up in the background so people thing imr eally smart and stuff

ill go to the library later today and then ill reallly show those homeless twats whos what

Okay this is making me mad.
There is no way to find f completely from pic rel?
You find f from the second statement, but end up with an expression with 2 unknown constants.
Then you can use the first statement to find one constant in terms of the other.
So ultimately you get f, but with one unknown constant in?

forgot pic

it's an adiabatic process

hyperphysics.phy-astr.gsu.edu/hbase/thermo/adiab.html