find the antiderivative of:

(x^3 - 5x^2 - 4) / (x^4 - 4x^2)

i used the difference of two squares to get it into this form

(x^3 - 5x^2 - 4) = (Ax + B)(x^2 - 2x) + (Cx + D)(x^2 - 2x)

but i can't seem to solve for A,B,C,D and I'm not getting any term equal to the -4 on the left side, what am i doing wrong

can someone post a step by step solution from this point onwards?