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/sci/ - Science & Math

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5436905 No.5436905[DELETED]  [Reply] [Original]

Hi i take multivariable calculus. i need help. please help.

>> No.5436909

>triple integrals

I don't think there are any math PhD's on /sci/.

>> No.5436913

>>5436909

They're all far too busy earning 300k startings of course.

>> No.5436919

Sorry I haven't passed Calc II yet.

>> No.5436937
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5436937

Math post-doc here. WTF is this shit? I can do quantum cohomologies, complex functional geometry and algebraic number theoretical analysis. But triple integrals? No way! That's way above my level. There's like 3 experts on triple integrals in the entire world and it's highly unlikely one of them browses 4chan.

>> No.5436939

>>5436909
Wut? Triple integrals are no more difficult than single, it's just an iteration.

>> No.5436954

>>5436939
Either you are trolling, a PhD, or a genius.
3/10 if trolling
If you are a PhD or genius, go brag about your IQ elsewhere, or help the OP

>> No.5436957

>>5436939
Are you Grigori Perelman?

>> No.5436994

In spherical,

theta from 0 to pi/2
phi from 0 to pi/2
rho from 0 to 1

integrand is rho^3 sin(phi) drho dphi dtheta

maybe

>> No.5436997

>>5436954
Not the same poster, but I never struggled with triple integrals in multivariate calc. 4 pointed the class and barely showed up.

>> No.5437001

>>5436939
>>5436954
Integrating is not the hard part. Setting the integral up correctly is.

>> No.5437005
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5437005

>>5436997

>> No.5437010

<span class="math">\frac{2\pi}{3}[/spoiler]

I have a proof but the margin is too small.

>> No.5437043
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5437043

By inspection, the region you are integrating over looks like this.

The volume differential in cylindrical coordinates looks like this:
dV=rdzdrdθ

The volume differential in spherical coordinates looks like this:
dV=r^2sinφdrdφdθ

>> No.5437052

>>5437043
>The region is only inf the first octet*

>> No.5437138

>>5436994
that's what i got, just couldnt work out the limits. thanks for the help!

>> No.5437145

>>5437010
can you take a picture?

>> No.5437148

>>5437010
i got pi/8 :/

>> No.5437159

Bumping for a nice /sci/ styled refresher to triple integrals. If I just converted to spherical that first integral would be integrating from 0 to 1 over our 'radius' parameter, yeah?

>> No.5437194
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5437194

this is what i got
-OP

>> No.5437224

>>5437145
I can. Would you like me to?

>> No.5437228

>>5437224
that'd be great please..

>> No.5437238

>>5437228
I know it would be great. Would you like me to post the picture though?

>> No.5437241

>not doing math in ink
SHIGGYDIGGY

>> No.5437250

>>5437238
yes i would like you to post the picture.

>> No.5437252

>>5437250
I don't really feel like doing that.

>> No.5437277

>>5436937
made my day

>> No.5437322

spherical
r from 0 to 1, both angles from 0 to pi/2

cylindrical
r from 0 to 1, theta from 0 to pi/2, z from 0 to sqrt(1-r^2)

>> No.5437335

>>5437322
what are the intergrands?

>> No.5437373

>>5436905
oh god
i remember the time when i would see questions like this, skip a shit load of steps, write down the answer, and a bunch of points taken off