I understand how to do these, but I am stuck on how to solve for these 4 variables i got in these equations:

A + C = 2

B + D = 0

A + C = 0

B + D = 0

..just incase i messed up..my original equation is

integral of (2x^3)/((x^2 + 1))^2

So i did 2x^3)/(x^2 + 1)(x^2 + 1) = (Ax + B)/(x^2 + 1) +

(Cx + D)/(X^2 + 1)

I then got Ax^3 + Ax + Bx^2 + B + Cx^3 + Cx + Dx^2 + D

Then I got those 4 equations above...I am not seeing how to solve for the variables right now..maybe a brain fart.