# i have the answer i need the solution

• Dec 3rd 2012, 05:18 AM
Nervous
i have the answer i need the solution
Ok, i worked through a problem and got my answer which was wrong, so i checked the solution and i dont understand the last step:

:integration: 1/8 (1 - cos(2x) - cos^2(2x) +cos^3(2x)dx
=1/16x - 1/64sin(4x) - 1/48sin^3(2x) + C

Needless to say, i integrated the same thing and got something different, i tried differentiating the final answer in order to see what i should do, but nothing work for my feeble simian mind. (Happy)
• Dec 3rd 2012, 07:24 AM
coolge
Re: i have the answer i need the solution
The first term is x^2/16. I didn't check the other terms. integration x = x^2/2
• Dec 3rd 2012, 07:44 AM
Plato
Re: i have the answer i need the solution
Quote:

Originally Posted by Nervous
Ok, i worked through a problem and got my answer which was wrong, so i checked the solution and i dont understand the lasr step:

:integration: 1/8 (x - cos(x) - cos(2x) +cos^3(2x)dx
=1/16x - 1/64sin(4x) - 1/48sin^3(2x) + C

Have a look at this webpage.
• Dec 3rd 2012, 12:00 PM
Nervous
Re: i have the answer i need the solution
Quote:

Originally Posted by coolge
The first term is x^2/16. I didn't check the other terms. integration x = x^2/2

My apologies, that x was meant to be a 1. I'm on my girlfriends tablet, but I'll try to check before I hit enter next time.