This is a problem I am having trouble with:

$\displaystyle

\int 5xcos(5x) dx

$

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

$\displaystyle

\int udv = uv - \int vdu

$

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

$\displaystyle

xsin(5x) - \int sin(5x)

$