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1 messages · Page 12 of 1

barren notch
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h e l p im blanking out on a simple question

placid zinc
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Same as |x| = 2 + 1/x (for x ≠ 0, which is a solution)

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Worth trying to graph both

sage violet
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yeah

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hmmmmmmm

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actually

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try considering two cases: x < 0, x ≥ 0

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then see what happens

placid zinc
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That's a good idea too

barren notch
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i tried testing some values, but that got me nowhere

placid zinc
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Yeah, let's back up and do that instead. Pretend x is negative, then how can we rewrite the original equation to not include ||?

barren notch
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well we could first rearrange the equation like you said lxl = 2 + 1/x

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and if x is negative

placid zinc
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Ignore I said that haha it was dumb.

barren notch
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then the absolute value would make it positive right?

placid zinc
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So if x is negative, then |x| = -x

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That way, -x becomes positive

barren notch
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hmm

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wait nvm

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I was doing mathcounts trainer on aops

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and as I was entering the answer the problem changed

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:/

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thanks anyway

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.close

lone heartBOT
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placid zinc
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🤔

barren notch
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its a bug on aops

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i think its because aops was timed out for such a long time the problem changed

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idk its weird

barren notch
lone heartBOT
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barren notch
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its -1

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barren notch
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.close

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hybrid moon
lone heartBOT
hybrid moon
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(probability that the total after rolling 4 fair dice is 21) > (probability that the total after rolling 4 fair dice is 22)

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Can someone explain to me why its not equal

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Im using joseph blitzen statistics 110 course

rose sigil
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if you roll two 5 sided dice, is the probably of getting rolls that sum to 2 the same as getting rolls that sum to 7?

slow hound
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the way i think about it is like a bell ish shaped curve centered at the mean (3.5 * 4) that tapers off on both sides

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since 21 is closer to the mean than 22

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P(21) > P(22)

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@hybrid moon Has your question been resolved?

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small cypress
lone heartBOT
small cypress
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for m of AB i did (b-2)/(3-a) = 2

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for distance i did

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root (a+3)^2 + (2 + b)^2 = root 125

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after epxanding

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i got a^2 + 6a + 9 + 4 + 4b + b^2 = 125

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idk what to do from here

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a^2 + 6a - 112 + 4b + b^2 = 0

gray isle
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you have a system of equations \
$$\begin{cases}
\frac{b-2}{3-a} = 2 \ \
a^2 + 6a - 112 + 4b + b^2 = 0
\end{cases}$$ \
solve using something like substitution

ocean sealBOT
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ℝamonov

lone heartBOT
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@small cypress Has your question been resolved?

small cypress
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so like a is 1

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then b is 1

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smth like that

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quartz tusk
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Hello

lone heartBOT
quartz tusk
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So i was going through examples of set.

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and there was this example.

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"the collection of all boys in your class" and was mentioned that it is not a SET.

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WHY?

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oh pardon me guys.

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i read it incorrectly.

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sorry.

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/close

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.close

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tender dew
lone heartBOT
tender dew
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Is there a way to "tilt oscilations"?

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so that normal lines to a tangent in points k*pi would also be line of symmetry of 1 cosine mountain?

tacit arch
tender dew
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I know that what I can naturally picture doesn't come as easily in algebraic form

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hence my question

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guess there will be no symmetry since it's decreasing, unless I make oscilations to dampen in a step

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Idea of them tilting remains

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I think cosine must arise from a tangent, but not sure how to create it

lone heartBOT
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@tender dew Has your question been resolved?

tacit arch
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I think the main problem is your tilt is different for every point. So it's not really useful to think of how to map g to h. Instead just decide how to map f to h directly. This can be done by finding the perpendicular line at every point, then calculate the amplitude in direction using the cosine and exponential, or maybe that's just g. This will probably have to be done using parametric form

tacit arch
tender dew
tender dew
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"I think the main problem is your tilt is different for every point."

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that part

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I wonder how to create perpendiculars for every point, whether I can rewrite mathematically, this thing will require to solve linears for every point with a = -1/f'(x). In program everything would be possible, but can 1 equation express desired function at the end?

tacit arch
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Yea that's the right direction. You just need to find amplitude. Again, gotta do it parametrically

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Also, once you have the normal vectors using -1/f', you have to move it to the curve f

tender dew
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so is it confirmed that there is no 1 equation?

tacit arch
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I never said that

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You should try

tender dew
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linears

tacit arch
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Oh. Then yes. Your normal vector will be different at every point

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The only thing that has a constant normal vector is a line

tender dew
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different A and different B

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maybe finding patterns in them changing will help

tacit arch
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It's just calculating -1/f' for a couple periods

tender dew
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hmmm, seems like tampered hiperbolic function

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how B changes

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bit ridiculous

tacit arch
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That only gets you the directions

tender dew
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What desmos did is probably draw infinitely many perpendiculars that would take up an entire plane, but all are calculated on a line of original function

tacit arch
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I told you to find the amplitude and do parametrization. I already said you won't be able to find a function

tender dew
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I knew he won't be able to draw h(x) but that was worth a try

tender dew
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altough for every point it probably turned out that bad

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I try solve discretely now

tender dew
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it may seem like it, but they don't pass by the same point

tender dew
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was wondering whether this spot makes some finite are but I guess with every new normal it increases in size faster than argument arise

paper ridge
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This took way too long, but I got something

lone heartBOT
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@tender dew Has your question been resolved?

tender dew
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looks like you used desmos too

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I mean I wonder how you got an amplitude

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I had one idea to calculate cos times f(x) being sqrt(deltax^2 + deltay^2)

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but doing so many calculations for 1 point is nuts

paper ridge
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depends what "that way" is, I was trying to do something with rotations but it got ugly, then I found a simpler way to do it by accident

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here it is all cleaned up

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square wave on exp 🙂

tender dew
paper ridge
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I'm assuming your talking about this part?

tender dew
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I think I understand why calculate derivative to it's module since I wanted do it as well to get the length of normal vectors along parent function f(x) but why twice?

paper ridge
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Are you good with the first part to get the unit tangent?

paper ridge
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The normal vector to a curve is usually defined using the arclength parameter (as far as I've seen), but using chain rule and FTC I think it should be the same in the standard parameterization, hence why I do it again

tender dew
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.close

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lone heartBOT
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tender dew
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welp, x^n is not a signal but generaliation of such

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I can use matlab for it

tender dew
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OK, I recalled a bit of this and that

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I knew that this peak at x = 0 is in effect of spectral leakage

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The Fourier transform of a function of time, s(t), is a complex-valued function of frequency, S(f), often referred to as a frequency spectrum. Any linear time-invariant operation on s(t) produces a new spectrum of the form H(f)•S(f), which changes the relative magnitudes and/or angles (phase) of the non-zero values of S(f). Any other type of o...

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unfortunately I no longer have access to program that rid that

lone heartBOT
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@alpine sable Has your question been resolved?

tender dew
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it's about removing offset from signal

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signal = signal-mean(signal);

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that still gives back peak at 0

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welp, no signal closer to harmonic so maybe it should be this way

alpine sable
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What is mat lab

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plucky geyser
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I just wanna say that's a good question you know

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I'm just kidding

lone heartBOT
#

@alpine sable Has your question been resolved?

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@alpine sable Has your question been resolved?

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alpine sable
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no clue what to do with this integral

lone heartBOT
alpine sable
rose olive
#

How do i move farword

alpine sable
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im using this channel sorry

lone heartBOT
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@alpine sable Has your question been resolved?

fallen venture
alpine sable
#

<@&286206848099549185>

fallen venture
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So essentially

alpine sable
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im all ears

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one sec im gonna get some water

fallen venture
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You get the integral itself

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When you do integration by parts

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And you let I = to the integral

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Substitute

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And solve for I

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So if you let I = to the integral

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You get

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I = (e^2x sin(x/2))/2 - 1/4 I

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Then solve

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Oh wait

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Nvm

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You need to do integration by parts again

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And then you can do that

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So the cosine turns into sine

alpine sable
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wtf is this evil ass integral

fallen venture
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Do integration by parts

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Then do the method above

alpine sable
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what

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im confused

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if i do integration by parts i cant get any further

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i just get stuck at this

fallen venture
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do IBP on the cos e^x integral

alpine sable
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whats IBP

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oh

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integration by parts

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okay

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one second

fallen venture
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And then you can substitute I for the integral

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And solve

alpine sable
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so i create a double integral?

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im kinda confused

fallen venture
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Anyways i gotta go

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Cya and gl

alpine sable
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ok

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cya

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ty

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<@&286206848099549185>

alpine sable
#

.close

lone heartBOT
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tidal zealot
lone heartBOT
worn fox
#

Do you know any graphs that are continuous at a point but not differentiable there? Not asking for at x=1 yet

tidal zealot
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no

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what does it mean by non differetiable

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how is something not able to be diffrentiated

worn fox
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That the derivative does not exist at that point

tidal zealot
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so how would that happen

worn fox
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Well what's your definition of the derivative at a point?

tidal zealot
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gradiant

worn fox
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Just gradient?

tidal zealot
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yeah?

worn fox
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Alright

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,w plot |x|

worn fox
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What do you think the gradient is at x=0 of this function

tidal zealot
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0

mellow tusk
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@worn fox would this work ?

mortal trellis
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that's not continuous

tidal zealot
#

discontinuos

mellow tusk
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oh

mellow tusk
karmic rapids
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discontinuous graph at point X

mellow tusk
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okay

worn fox
tidal zealot
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then wht else would it be

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or would it be underfined?

worn fox
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Yes there is our issue

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There's no sensible value to assign to the derivative at that point

tidal zealot
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okay?

worn fox
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1 and -1 seem like good choices from certain perspectives

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But there is no agreement

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So it's not differentiable at that point

tidal zealot
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oh

worn fox
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(Lots of maths rigour is hidden behind my words)

tidal zealot
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okay

mellow tusk
worn fox
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But you would agree its continuous at that point

tidal zealot
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yes

tidal zealot
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so how would i make one for my question at x=1

mellow tusk
worn fox
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Well if |x| satisfies the condition at x=0, how can we transform this graph to make kt satisfy it at x=1?

karmic rapids
tidal zealot
karmic rapids
#

open your own help channel btw

tidal zealot
mellow tusk
mellow tusk
#

nvm i got it ig

worn fox
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What's the equation of that graph

tidal zealot
#

|x-1|

worn fox
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Very good

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And you agree that it's continuous at x=1 but not differentiable there

tidal zealot
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yes

worn fox
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Awesome

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Good job

tidal zealot
#

ok thank you, i have learnedd something today

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.close

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mellow tusk
lone heartBOT
alpine sable
#

first make sure that the first function's limit as x approaches 0 is 0

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make sure that $e^{\frac{-1}{x^2}}\sin\frac{1}{x}$ approaches 0 as x approaches 0

ocean sealBOT
#

Legolas

mellow tusk
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x->0+ , e^-inf * sin 1/h=0, x->0- ,e^-inf * -sin 1/h=0, thats why its continuous
was my first step right?

alpine sable
#

Yeah

mellow tusk
# mellow tusk

i cant solve the lhd and rhd (left and right hand derivatives )

alpine sable
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so now we know the derivative exists

mellow tusk
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they're basically lim h , f(h)/h

mellow tusk
alpine sable
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Oh yeah

#

mb

mellow tusk
lone heartBOT
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@mellow tusk Has your question been resolved?

mellow tusk
#

<@&286206848099549185>

lone heartBOT
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@mellow tusk Has your question been resolved?

mellow tusk
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.close

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hallow vessel
#

was looking for help with matlab

lone heartBOT
hallow vessel
#

is this smth that anyone could help w?

worn fox
#

post your Q, if someone sees it and can help they will

hallow vessel
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ok cool

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Im trying to make a monte carlo integration sim

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and am new to matlab

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how do i pick random points in a set domain

worn fox
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MATLAB has a random function i imagine

hallow vessel
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i tried using it and it doesnt work how i want it to

worn fox
#

explain how you want it to work

hallow vessel
#

1 sec

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im looking to make it pick a random coordinate in between the bounds of [-2 2 -2 2]

worn fox
hallow vessel
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that was in the matlab help??

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bruh i must be blind

worn fox
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yes lol

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like one scroll down

hallow vessel
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ohhhh

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i think i typed it wrong earlier

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i was using the inbuilt matlab guide

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ill give it a try

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ok so

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i get returned a 2xn

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but i neeed to then check if these pairs lie within an area

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does anyone have any help?

lone heartBOT
#

@hallow vessel Has your question been resolved?

lone heartBOT
#

@hallow vessel Has your question been resolved?

lone heartBOT
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@hallow vessel Has your question been resolved?

lone heartBOT
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@hallow vessel Has your question been resolved?

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vital steeple
#

Hi

lone heartBOT
vital steeple
#

Is the following proof correct?

#

$\begin{align*}
&M_3 = {(a_1, b_1), (a_2, b_2), ..., (a_k, b_k)} \subseteq A = \mathbb{N} \times \mathbb{N}
\
&\text{Let poset } \leq \text{ be defined as } (a,b) \leq (c,d) \Leftrightarrow a \leq c \land b \leq d.
\
&\text{Show that Supremum exists.}
\\
&\text{My try at this:}
\
&\underline{\text{1st case:}}\text{ Let } a \in M_3 \text{ with } a = (a_s, b_s), a' \in M_3 \text{ with } a' = (a_i, b_i), s.t.
\
&a_i \leq a_s \land b_i \leq a_s. a \text{ is per definition maximum and thus supremum of } M_3.
\\
&\underline{\text{2nd case:}} \text{ Assume there is no maximum in } M_3.
\&\text{Then there's no supremum being element of } M_3.
\
&\text{Yet there could be a supremum of } M_3 \text{ in A as a superset.}
\
&\text{Let } b=(a_s, b_s) \in A, \text{ arbitrary } b'=(a_i, b_i) \in M_3:
\&b \notin M_3 \land a_i \leq a_s \land b_i \leq b_s
\Rightarrow b \text{ upper bound of } M_3.
\
&\text{Yet to show is that b is lowest upper bound of } M_3 \text{ and so supremum. So let be...}
\
&b''=(a_j, b_j) \text{ is arbitrary upper bound of } M_3 \text{ s.t. }
\
&a_i \leq a_s \leq a_j \land b_i \leq b_s \leq b_j \Rightarrow \text{b is supremum of } M_3.
\
\end{align*}$

ocean sealBOT
#

tarık b.
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

vital steeple
#

Small addition: To be shown is that Supremum exists for M_3

wanton nova
#

Tarik Barletti

alpine sable
#

Tarik Barletti

vital steeple
#

first time hearing that game figure

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Tarık's my name, 'B' the initial of my surname

wanton nova
#

Nice

gloomy wolf
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i am not sure about your proof

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this seems like it wants to be argued inductively

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try induction on k

vital steeple
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What doesn't seem to work in my proof? And how would I do induction on k?

gloomy wolf
#

eh actually i think i misunderstood your argument

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this should do it

lone heartBOT
#

@vital steeple Has your question been resolved?

vital steeple
#

thanks James

lone heartBOT
#
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pseudo spear
#

How can I prove the following:

lone heartBOT
pseudo spear
#

$e^x+ e^{-x} \leq 2 \cdot e^{x^2}$

ocean sealBOT
#

gnomechomsky

pseudo spear
#

Seems right to me but im not sure if I can make it simlper

tacit arch
#

,w plot 2 e^(x^2) - e^x - e^(-x)

pseudo spear
#

oh I guess not

#

Oh no wait, that is right

#

It never goes negative, meaning it is right

#

But how would I show it more simply?

tacit arch
#

,w plot e^(x^2) - e^(-x) for -1 < x <1

pseudo spear
#

Oh right

worn fox
#

man of many words

tacit arch
#

i imagine it's grouping 2e^(x^2) the right way to bound each term on the left individually

pseudo spear
#

Im not sure what you mean

#

After playing around with it a bit I think it is right, but im not sure how to show it

molten pivot
#

Hello

#

Combine the fraction on lhs

paper ridge
#

Are you familiar with the hyperbolic trig functions @pseudo spear ?

pseudo spear
#

not really

paper ridge
#

This one is most useful here. It's an even function and strictly increasing for $x>0$, so $\cosh(x)\leq\cosh(x^2)$ for all $x$

ocean sealBOT
#

Tymelord14

ancient moss
#

that’s not right

worn fox
#

not for |x| < 1 😦

paper ridge
#

ah, good point

worn fox
#

i personally don't care much for (-1,1) lets just be gone with it

pseudo spear
#

Thanks for the help anyway guys but I'd best sleep now

#

.close

lone heartBOT
#
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still storm
#

I have done part a, but how do I construct this right-handed orthonormal frame along the curve? can someone please help

naive valley
#

well you showed in part (a) that the acceleration is orthogonal to the velocity, and in part (b) you're given that these are both nonzero, so you have two out of the three components you need for an orthogonal frame

#

given two orthogonal vectors in R3, do you know how to construct a third that is orthogonal to the first two?

still storm
#

can I use gram-schmidt?

naive valley
#

no it's simpler than that

#

an operation on the first two vectors that produces a third

still storm
#

cross product?

#

but how do I make sure it is along the curve?

naive valley
#

well the velocity is tangent to the curve right?

still storm
#

yes 🙂

naive valley
#

so doesn't that automatically make the frame "along the curve"? (not sure exactly what you mean by that)

still storm
#

because in question it ask for the frame along the curve(

naive valley
#

the only remaining steps: you probably want to normalize the vectors to make them unit vectors, and you should check that it is in fact a right-hand frame as requested

#

for the right-hand part: only one of (vel x acc) or (acc x vel) will satisfy the requirement, so make sure you know which one you need

still storm
#

ok, that make sense alot

#

can I ask you another question?

naive valley
#

sure

still storm
#

is that one

#

for a

#

I'm not sure about derivative of r(f(t))

naive valley
#

ok, well as in part (a) of the previous question, the speed will be constant if and only if $|\frac{d}{dt}r(f(t))|$ is constant, or equivalently if and only if $|\frac{d}{dt}r(f(t))|^2$ is constant

#

probably easiest to work with the squared version

#

so you won't have a square root to deal with

still storm
#

please wait for a min, I'm taking pic of my work

ocean sealBOT
still storm
#

sorry, the picture is not working. so my question is if I have r(t)=(1,t^2), f(t)= 2t, then is r'(f(t))=(0,8t) or (0,4t)?

#

like do I substitute f(t) into r' directly or I have to substitute into r and take the derivative of r(f(t))

naive valley
#

well, r'(t) = (0, 2t), so r'(f(t)) = (0, 2(2t)) = (0, 4t)

#

however

#

you don't want r'(f(t)), you want d/dt r(f(t)), which involves the chain rule

still storm
#

so d/dt r(f(t)) = r'(f(t)) * f'(t)

naive valley
#

yes

still storm
#

that's where I stuck

naive valley
#

well as above, r'(f(t)) = (0, 4t)

#

what's f'(t) ?

still storm
#

2

naive valley
#

right

#

so d/dt r(f(t)) = r'(f(t))f'(t) = (0, 4t)2 = (0, 8t)

still storm
#

yep, I get to here, but I don't know how to find a general f(t) s.t. every speed is constant

naive valley
#

well they're asking for a differntial equation, not a solution to the equation

still storm
#

emm, what's the difference?

naive valley
#

so depending on how much you want to simplify, it's just $|r'(f(t))f'(t)| = c$ right?

ocean sealBOT
still storm
#

yes

naive valley
#

a differential equation is an equation involving derivatives of functions, a solution is a function or functions that satisfy that equation

#

in parts (a) and (b) they're just asking for equations, in part (c) they want a solution (I think)

still storm
#

ok... so if I have f'(t)^2=c/|r'(f(t))|, is that correct

#

$f'(t)^2 = c/|r'(f(t))|$

ocean sealBOT
naive valley
#

no, either everything should be squared or nothing should be squared, depending on whether you're working with speed or speed squared

still storm
#

$f'(t) = c/|r'(f(t))|$ ?

ocean sealBOT
still storm
#

Do I need to keep going

naive valley
#

LHS should be |f'(t)|

#

RHS should technically be ||r'(f(t))|| in the denominator since r' is a vector

still storm
#

right, I get it, do you think that's everything for part a?

#

should I go ∫

naive valley
#

I'm not sure that's really any more simplified than the original form $|r'(f(t))f'(t)| = c$ or maybe (pulling out $f(t)$ since it's a scalar), $|r'(f(t))||f'(t)| = c$, but in any case you can't really simplify much beyond that without knowing the specific $r$

still storm
#

or I can leave this as the answer

ocean sealBOT
naive valley
#

no if it's asking for a differential equation then definitely don't integrate it

still storm
#

ok, I get it. thanks a lot!

#

.close

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craggy summit
#

Can you give an example of a set $S$ with $|S| > 1$ and a formula $\varphi$ such that $(\exists x \in S)\varphi(x) \rightarrow (\forall x \in S)\varphi(x)$?

ocean sealBOT
lone heartBOT
#

@craggy summit Has your question been resolved?

tacit arch
lone heartBOT
#

@craggy summit Has your question been resolved?

craggy summit
#

yeah I guess that would work. That's not a very interesting example though

lone heartBOT
#

@craggy summit Has your question been resolved?

swift shore
#

@craggy summit by “formula” do you mean a predicate function?

#

Like it takes an argument and returns true/false

tacit arch
#

Show the original question if it's from homework or text book

swift shore
#

@craggy summit hmm after thinking about this for a bit

#

I think phi has to relate to the other elements of S somehow

#

Because if phi is just some random quality of x, who says it dictates anything about the rest of S?

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keen sinew
#

Hello,

I derived to get the answer and the interpretation is to get the instataneous rate of change wrt concentration of a substrate

keen sinew
#

I guess what im trying to rap around my head is when do I know when i should just find the an answer without the derivative

swift shore
#

Wdym “when to find the answer without the derivative”

#

Like, generally speaking? Not this problem?

keen sinew
#

yes

#

I guess what im trying to resolve is that a biologist would use it to find the rate rate of the reaction

But they would react to find the rate of change on the reaction through deriving?

swift shore
#

Well it depends on the problem of course

#

Hmm

keen sinew
#

i guess what im trying to say is that we just derive to find the instant change of a function?

#

like if im driving, i know im going at x amount of miles per hour

but if i derive one time i get velocity

derive twice acceleration

derive thrice I get the jerk?

swift shore
#

Yeah

#

Well this is a little hard

keen sinew
#

yea sorry about that

swift shore
#

Basically you’re seeing how a small change in S, the concentration, will affect the speed of the reaction

keen sinew
#

right as h -> 0

swift shore
#

No it’s not your fault lol

#

Yep

#

I mean it’s all a little abstract, I’m not sure how you’d apply it exactly lol

keen sinew
#

ive always been bad at math so im trying to get better at it

#

thank you!

swift shore
#

Np don’t worry bout it

keen sinew
#

.close

lone heartBOT
#
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swift shore
#

you definitely know what’s going on 🙂

lone heartBOT
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thin urchin
lone heartBOT
thin urchin
#

I am thinking 3^3 or 3!

#

but I could be way off

#

this is one of those challenge questions that is not like the other questions

tight locust
#

'derangement'

oak perch
#

$\sum_{k=0}^{n}(-1)^{k}\binom{n}{k}(n-k)!$

ocean sealBOT
#

Cogwheels of the mind

oak perch
#

Now plug in n=4

thin urchin
#

hmmm

#

they didnt teach the inclusion-exclusion principle to us in sum form

oak perch
#

You can prove it yourself, it’s easy

thin urchin
#

ok so a sum of 0 to n in negatives multiplied by n choose k multiplied by the factorial of n-k?

oak perch
#

Also (-1)^k

thin urchin
#

oh

#

that looks pretty general, is it just the -1 that is specific to this problem or is that just the general formula for these kind of problems?

oak perch
#

Don’t know what you are talking about.

#

Inclusion-exclusion principle is a general result

thin urchin
#

oh

#

they tought us like (A U B U C) = A + B + C - (A n B) etc

#

we certainly did not learn matricies yet

oak perch
#

Then direct counting

thin urchin
#

ok

#

I just need a little help setting it up for direct counting

oak perch
#

|A_1 union …. union A_n|=|A_1|+…+|A_n|-|A_1 intersection A_2|-….+|A_1 intersection A_2 intersection A_3|*…

#

To prove this

#

Compare both sides

#

Any x from A_1 union … union A_n

#

Say x belongs to m many sets amount A_1,…,A_n

#

For LHS, x is counted exactly one time

#

For RHS

#

x is counted

#

$\sum_{k=1}^{m}(-1)^{k-1}\binom{m}{k}=1$

ocean sealBOT
#

Cogwheels of the mind

oak perch
#

Times

#

Therefore x is counted for exactly one time both sides

#

QED

lone heartBOT
#

@thin urchin Has your question been resolved?

thin urchin
#

hmm ok

#

thanks

#

.close

lone heartBOT
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crimson solstice
lone heartBOT
crimson solstice
#

for this

#

on the left

#

would i apply the product rule to cos(xy) * y and then apply the chain rule to cosine then apply the product rule to xy?

tacit arch
#

sounds right

#

share your work here if you want to check it

crimson solstice
#

yeah doing it rn

#

bout to send it cuz i think im stuck just a sec

crimson solstice
#

not sure what to do past here

#

also not sure if i found the dy/dx of cos(xy) correctly here

tacit arch
#

all looks right

#

just use algebra and solve for dy/dx

#

if it helps, set z = dy/dx and solve for z

crimson solstice
tacit arch
#

no

crimson solstice
#

hmm

#

but if there is dy/dx on both sides how would i get rid of one of them

tacit arch
#

z + 2z * cos(x) = 3z * log(x). how do you solve for z?

crimson solstice
#

divide 3z by both sides

#

wait

#

i dunno

tacit arch
#

bah bad example. i'll fix it

#

z + 2z * cos(x) + tan(x) = 3z * log(x). how do you solve for z?

crimson solstice
#

hmm

#

would you move all z to left side and factor a z out?

tacit arch
#

do the same for dy/dx

crimson solstice
#

ok let me distribute

#

then going to try that

#

worked!

#

tysm

#

incredibly helpful man ty

tacit arch
crimson solstice
#

just have one more question

#

i think i messed up on this one

#

so im here

#

wait

#

ok i think i messed up here cuz the answer isnt correct but im not sure where

tacit arch
#

Can't read the initial equation

#

It's that a y?

crimson solstice
#

yeah'

#

sorry

#

y = 2cos(x+y)

lone heartBOT
#

@crimson solstice Has your question been resolved?

tacit arch
#

i don't know how y' became 2

lone heartBOT
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atomic comet
#

I am getting D but answer given is A and B,how? What is the mistake in my process?

tacit arch
#

,w plot x + sqrt(x) - 6

tacit arch
#

(A) is definitely wrong

oak perch
#

a+sqrt(a)-2<4

#

By the way Riemann that problem is solved, f(f(x)+f(y)) thing, I proved it can only be constant 0

oak perch
#

Not this problem you asked, another problem we were discussing

atomic comet
oak perch
#

So I got -3<sqrt(a)<2, since a>0, I got 0<a<4

atomic comet
#

So the answer given is wrong,i suppose

oak perch
#

Probably

atomic comet
#

Okay I see

#

Thanks for confirming

oak perch
#

Np

atomic comet
#

.close

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thin urchin
lone heartBOT
thin urchin
#

am i way off?

#

for part a

#

<@&286206848099549185>

lone heartBOT
#

@thin urchin Has your question been resolved?

lone heartBOT
#

@thin urchin Has your question been resolved?

tidal lantern
#

First you chose one ace from the four in the deck : C(4,1) ways to choose, then you choose 4 others cards which aren’t aces C(48,4) possibility

#

The probability of taking a card is equal for all cards, so the probability is given by the number of hands which contains one ace and the total of hands possible

lone heartBOT
#

@thin urchin Has your question been resolved?

lone heartBOT
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west dirge
#

Hi

lone heartBOT
west dirge
#

Trying to do this question

#

what ive tried so far is

#

subbing in z = x + yi

#

then using the Cauchy Riemann equation to see where it is differentiable

#

these are what i get

#

but not too sure how to express where it is differentiable nicely

#

and how to format the derivative

lone heartBOT
#

@west dirge Has your question been resolved?

lone heartBOT
#

@west dirge Has your question been resolved?

lone heartBOT
#

@west dirge Has your question been resolved?

lone heartBOT
#

@west dirge Has your question been resolved?

elfin snow
tidal lantern
#

You made a sign mistake for the cosinus formula, not sure if it will solve your problem though

lone heartBOT
#

@west dirge Has your question been resolved?

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alpine sable
#

pls help

lone heartBOT
alpine sable
#

i don't even know where to start on this one lol

placid zinc
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kindred crater
#

I'm having trouble with u substitution. Where does the du go in this step?

kindred crater
#

oh so when you do the integral the du disappears with it?

tacit arch
#

yes. same for any integrating variable

#

$\int x^n dx = \frac{x^{n+1}}{n+1} + C$

ocean sealBOT
#

riemann

tacit arch
kindred crater
#

Another question, in this step (pic attached), how does the 4x^5 dx disappear when plugging it back into the original integral?

#

it turns into this

#

-1/12du = 4x^5dx. So does it just simply replace the original variables there?

worn fox
#

Yes 4x⁵ dx is being replaced with -1/12 du

kindred crater
#

alright, I think I understand it now then. thanks guys

#

.close

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ebon prawn
lone heartBOT
ebon prawn
#

Im not sure on how to progress from there but can I add both of the logarithms on the left to make it 1/2 log x

placid zinc
#

What was the original question?

ebon prawn
#

Its in there

#

Below the x=1 x=-1

abstract badge
#

whenever you have a+b and a-b try to reach a place where those 2 terms multiply

#

use the product rule

#

@ebon prawn

placid zinc
#

Hint, the left can be written as:
log(√[x+2]) + log(√[x-2])

#

Once that happens, you can combine the logs using the log product rule

lone heartBOT
#

@ebon prawn Has your question been resolved?

abstract badge
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ebon prawn
#

Sorry for not replying, i solved the problem but I was eating

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#

@mossy talon Has your question been resolved?

mossy talon
#

<@&286206848099549185>

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@mossy talon Has your question been resolved?

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@mossy talon Has your question been resolved?

elfin snow
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unreal kiln
#

Claimed

lone heartBOT
unreal kiln
#

How do I create one that satisfies both

wary stream
unreal kiln
#

Assignment

#

It’s worth marks tho

wary stream
#

So like a homework, where you can get outside help?

unreal kiln
#

Yeah

#

Completion marks

#

@wary stream can you help?

tacit arch
#

Non permissible means you can't define the function at those points

#

No idea about x=y though

lone heartBOT
#

@unreal kiln Has your question been resolved?

unreal kiln
#

I need an example

glass tree
#

(sorry read the wrong message)

unreal kiln
#

Ok

lone heartBOT
#

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old sentinel
#

I've got the question "The value of p^q - (digit sum of p)^2, where p and q are integers and q>=3 and the number is 5 digits long, is there any way to work out all the possible options easily?

lone heartBOT
#

@old sentinel Has your question been resolved?

old sentinel
#

<@&286206848099549185>

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@old sentinel Has your question been resolved?

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sharp jolt
lone heartBOT
obsidian plover
# sharp jolt

Are you familiar with domain and range? Have you tried these problems?

sharp jolt
#

I am familiar but I would need a review for this

obsidian plover
sharp jolt
#

(-inf,2]

#

?

obsidian plover
#

But the second part of the line continues doesn’t it?

#

If you go to x=3 you can still get a value

sharp jolt
#

It continues down wards

obsidian plover
#

Well diagonally

sharp jolt
#

Yeah that

obsidian plover
#

And that’s still increasing X

sharp jolt
#

Ooooh yeah your right

#

(-inf, +inf)

obsidian plover
#

Yep

#

Try range

sharp jolt
#

With the ()?

obsidian plover
#

Yea

sharp jolt
#

(-3,-inf]

obsidian plover
sharp jolt
#

(-inf,-3]

#

?

sharp jolt
obsidian plover
obsidian plover
sharp jolt
#

Apply

#

Like does that apply to domain and range ?

#

Or just range

obsidian plover
sharp jolt
#

Alrighty I’ll remember that by heart

#

How about c

#

I know for sure there is an x intercept for problem C

obsidian plover
#

X intercept is where the line touches the x axis

obsidian plover
sharp jolt
#

Idk 🥲

#

Wait so there isn’t one

#

Because it’s on the y axis

obsidian plover
#

Nothing hits x except the y axis which is an arbitrary line that is just a marker

sharp jolt
#

Wait but there is tho

#

So -3,1

#

Wait so if it hits the y axis what do I put?

obsidian plover
#

theres no x intercept

sharp jolt
#

Pretty sure this answer key is wrong

obsidian plover
sharp jolt
#

Yeah so I was right

#

There is no x intercept

lone heartBOT
#

@sharp jolt Has your question been resolved?

sharp jolt
#

Actually yes

#

.close

lone heartBOT
#
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river remnant
#

Points P, Q, R and S in that order divides the line segment joining points A(2, 5) and B(7, - 5) in five equal parts. Find the coordinates of P, Q,

river remnant
#

Could anyone help me

desert tendon
#

u know section formula

lone heartBOT
#

@river remnant Has your question been resolved?

river remnant
oak chasm
#

Or, what is your answer?

river remnant
#

1.8, 3. I know it's wrong ASpeepoWeird

oak chasm
#

Yes, that's wrong.

#

Do you have a picture of what's going on drawn on paper?

wanton pebble
#

try to find ratio at which P and Q divide line segment

#

do you want ans? or want to know how to solve it

oak chasm
#

One of the rules is to not just give the answer.

#

It's OK to explain how to get it, though.

#

@river remnant How did you get 1.8? How did you get 3?

river remnant
#

Uhh, i putted section formula

oak chasm
#

OK, there's a little bit of a simpler method.

#

You take the x coordinates of A and B, and you do (Bₓ - Aₓ)/5 (the 5 is the number of sections).

#

That's how much each section will increase its x by.

#

So, like here, you have (7 - 2)/5 = 5/5 = 1.

#

So, A has 2 for its x.

#

P will have 3 for its x.

#

Q will have 4 for its x.

#

Because it's going up by 1 each time.

#

You can do the same thing with the ys.

#

(By - Ay)/5 will be how much to increase it by each time.

#

What do you get for that?

oak chasm
#

Kind of. The change in x of a section if all the sections are the same length.

#

@river remnant

#

You get the total change in x and divide it into 5 parts.

#

Because there are 5 sections.

river remnant
#

Did not get it but thanks

oak chasm
#

It's like if you have a string that's 150 cm long.

river remnant
#

Yes

oak chasm
#

If you cut it into 5 equal pieces, that's 150 cm/5 for each piece.

#

So, 30 cm for each piece.

river remnant
#

Yes

#

Oh

oak chasm
#

Same thing here.

river remnant
#

Right

lone heartBOT
#

@river remnant Has your question been resolved?

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lone heartBOT
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modest lava
#

how do I find the first 4 terms of the sequence a_n = 3n^2 - 5

alpine sable
#

substitute n=0,1,2,3 into the expression for a_n

modest lava
#

to be honest, these things still confuse me, can you show me what to do afterwards?

alpine sable
#

$a_{\color{red}0}=3\cdot\mathbf{\color{red}0}^2-5=3\cdot0-5=-5$

ocean sealBOT
modest lava
#

-2, 7, 22, 43

is this correct??
I dont know if this is right

alpine sable
#

yeah looks fine

modest lava
#

ohh nice

#

thanks

#

.close

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vast bobcat
lone heartBOT
vast bobcat
#

does anyone know how to prove part 2 and 3?

#

Especially the very last bullet point

lone heartBOT
#

@vast bobcat Has your question been resolved?

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tidal zealot
lone heartBOT
alpine sable
#

thats correct

tidal zealot
#

good

#

bcs this has no solutionsa

#

im sad

#

idk if im right ornot

#

.close

lone heartBOT
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hallow vessel
#

need help with an epsilon delta proof

lone heartBOT
hallow vessel
oak perch
#

Answered before

hallow vessel
#

i need some more help

#

i didnt really get it

oak perch
#

Any ε>0, there exists δ>0 such that any |h|<δ, we have |T(h)|<ε. So any |t|<δ/|v|, |T(tv)|<ε

#

I literally don’t know what else you need

hallow vessel
#

ohh i didnt see this i think

#

i mustve been v sleepy

#

but the part i dont know is getting to the delta value

oak perch
#

Really, two people asked the same question.

hallow vessel
#

delta/|v|

#

lmao

#

must be same course

oak perch
#

Check your definition

#

Your textbook

hallow vessel
#

of epsilon delta?

oak perch
#

Yeah. I already gave all details, the full proof

#

If you don’t get it check your textbook

#

Nothing more can be done

hallow vessel
#

bruh this icy cold

#

ok imma come back in 10 minutes, ill see if i can get it

#

.close

lone heartBOT
#
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vital root
#

What formula or function can one use to get the following output (Y) with the given input (X)?

 x  | y 
1.00| 0
0.10| 1
0.01| 2

So on and so forth, where every 1/10th step increases Y by 1.

vital root
#

I'm thinking it's a logarithmic scale but I can't for the life of me figure out what specifically

#

It's like reverse logarithmic

#

Doh, I got it: log0.1(x)

#

.close

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keen lance
#

How do I make a pair of simultaneous equations with whats given for (a)?

alpine sable
#

eg, 4x+4=5x and 5x=60y-100

keen lance
#

i see

#

thanks

#

.close

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vestal pilot
#

Linear algebra
What does doing this mean?

alpine sable
#

weird

#

it means "T is a map from the kernel of T to the image of T"

#

which makes no sense at all lol

vestal pilot
#

I had to find the Ker(T) and Im(T) of the transformation I got, and then they ask me to find the transformation matrix of T after the reduction with respect to the basis that I found in the beginning

#

Wouldn't doing Ker to anything give me a 0 vector

alpine sable
#

yeah

vestal pilot
#

Oh wait maybe because Im(T) is the image, then it equals to W in V->W

alpine sable
#

if T is only defined on its kernel, then its the zero map

vestal pilot
#

And that would mean that Ker(T)={0}

alpine sable
#

I dont understand whats going on in your picture, sorry

vestal pilot
#

I was just finding the Ker and Im

alpine sable
#

that part looks fine

vestal pilot
#

Oh, you mean the first picture

#

I mean doing Ker(T)->Im(T) is not wrong

#

I've seen it done a ton of times

#

I just don't remember what it means

lone heartBOT
#

@vestal pilot Has your question been resolved?

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strange fractal
#

hi!

lone heartBOT
strange fractal
#

i need help

#

nvm

hollow vapor
strange fractal
#

i need more hel

hollow vapor
#

ok

#

?

strange fractal
#

nvm!

hollow vapor
#

ok-

lone heartBOT
#

@strange fractal Has your question been resolved?

strange fractal
#

question

#

why is it 1/16

#

i gotthis

#

<@&286206848099549185>

alpine sable
#

2/32=1/16

strange fractal
#

but if i bring the 2 over from other side

#

it's -2

#

?

#

@alpine sable

alpine sable
#

divide both sides by 32

strange fractal
#

why?

#

OH

#

TYMSM

alpine sable
#

yw

lone heartBOT
#

@strange fractal Has your question been resolved?

lone heartBOT
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sage violet
#

wdym\

#

y = x ?

alpine sable
#

Try x log x

lone heartBOT
#

@runic lark Has your question been resolved?

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ashen copper
#

This is a question about Monte Carlo Algorithm
I just read about this algorithm recently
I would like to know how I may apply this
In a game of 5 our side units and 1 opponent enemy unit
Each units create damage on enemy
In the contrary, the enemy also create damage to our units.
The Total Damage is the accumulate damage where our units made to the enemy unit.
Each units has a CriticalRate.
Normally the CriticalDamageRate is 2; but based on buff and debuff this could changed.
Also each game could have different seed.
Now the question is that how do I apply Monte Carlo Algorithm so I can get the Expected Accumulated Damage that is trustful

inland oriole
#

What is a Cartesian product?

worn fox
lone heartBOT
#

@ashen copper Has your question been resolved?

lone heartBOT
#

@ashen copper Has your question been resolved?

noble sinew
ashen copper
#

I am actually trying to ask the math of this

#

As like I don’t quite understand how to use this algorithm

elfin snow
ashen copper
#

Okay

noble sinew
#

Its just a class of algorithms which use simulation

#

And what I said is how you use that

ashen copper
#

So for each hit of an attack I will be able to get a damageData with the following information
NonCriticalDamage
CriticalDamage
CriticalRate

#

I think I should use the formula
NonCrit*(1-critrate)+crit*critrate?

noble sinew
#

Sure if u want to

lone heartBOT
#

@ashen copper Has your question been resolved?

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still lynx
#

Hello, i would like to get a bit of help on this one I try to multiplicateur by sinx-cosx but doesn’t work

dusk moth
#

Which one

#

1 or 2

marsh rapids
#

That is a good idea

#

It does simplify nicely. Just go a bit deeper with that idea

dusk moth
#

The first one

lone heartBOT
#

@still lynx Has your question been resolved?

still lynx
#

Yes 1

#

I am now stuck with (sin(2x)-1)/cos(2x) < 0

#

How am I suppose to solve this ?

lone heartBOT
#

@still lynx Has your question been resolved?