I have this problem (forgive me, i haven't gotten the math controls down yet):

Integral 7x/(1+3x^2)^2 dx

here's what I've done so far:

A/(1+3x^2) + B/(1+3x^2)^2

= A(1+3x^2)+B(1+3x^2)/ (1+3x^2)^2

= A(1+3x^2)+B

I'm stuck right there. I can't figure out how to solve for A and B. Any help is greatly appreciated.

Cheers