/sci/ - Science & Math

[Anonymous No.1515867]

So, exam next week and I still can't integrate trigonometric functions properly. I'm fucked. Someone help me integrate cos^4x That's cosx to the power of 4 not as a coeffictient! Please help otherwise I'm more than likely gonna paint the walls with my brain.

inb4 trolls making me fail my exam

[Anonymous No.1515870]

>Phd in mathematics
>any jon i want
>300k weekend

[Anonymous No.1515876]

<div class="math">I = \int \cos^4 x dx</div>

Use integration by parts until you find I again. Solve for I.

[Anonymous No.1515881]

>>1515867
go to khanacademy.org it will do more for you to watch the videos there than try to separate troll from legit here.

[Anonymous No.1515921]

seriously?
int[cos(x)^4 dx] = int[cos(x)^2 * cos(x)^2 dx]
use integration by parts

[mc No.1515937]

I = (cos^4 x)
I = (cos^2 x)^2
cos^2 x = .5 + .5cos 2x
I = .25 + .5cos2x + .25cos^2 2x
And you can integrate that.

[Anonymous No.1516027]

Oh god I passed that mental wall. I'm and idiot it was just chain rule. Too much math study is counterproductive to normal study.

[Anonymous No.1517310]

>>1515876

no. make a reduction formula for I = S cos^n(x) dx, then just sub n=4 into that until your integral comes out.

shit's pretty efficient, brah - will either reduce the integral to power of one so it's simply soluble, or solve it all the way

[Anonymous No.1517353]

why doesn't anybody use the jsMath?
It looks awesome and makes equations easy to read.

DO EET!

[Inox !ftPf.M4w3U No.1517373]

>>1517353
I would totally use the fuck out of it
especially because writing stuff like (x-1)/(x+1) or exponents or stuff looks incredibly shitty without it

but first I have to lrn2jsMath