It's on the tip of my tongue and I can't remember a trick I remember learning to solve these.

$\displaystyle

\frac{3}{(x+2b)(x-b)} + \frac{2}{(3b-x)(x+2b)} + \frac{1}{(x-3b)(b-x)}

$

For some reason i feel like there was a trick where you switch the signs and cross multiplied or something like that to get the denominators the same...but i cant remember

or do i just have to do it the long way and multiply a million times

Thanks