Thread: [SOLVED] Integration by parts

This is a problem I am having trouble with:


This is the formula we were taught in class to use for these types of problems:


I came up with this but I am sure it's wrong.

Originally Posted by redman223

This is a problem I am having trouble with:


This is the formula we were taught in class to use for these types of problems:


I came up with this but I am sure it's wrong.

yes, it's incorrect. did you identify your u and dv? show your steps so we see where you went wrong.

I set u=5x du=5 dv=cos(5x) and v=1/5 sin(5x)

That gave me:


I tried to use -1/5x cos(5x) for the part in the integral but it is still wrong.

Originally Posted by redman223

I set u=5x du=5 dv=cos(5x) and v=1/5 sin(5x)

That gave me:


I tried to use -1/5x cos(5x) for the part in the integral but it is still wrong.

that is correct. all you need to do now is find and wrap it up

Thanks, for some reason I kept thinking that the derivative of 5x was 5x and not 5, lol.

I came up with -1/5 cos(5x) and it was correct. Thanks.