How can I find the primitive of $(x^3+x^2)/(4-x^2)$? I’m trying to find the primitive of the below rational function. I’m stuck trying to separate the undetermined coefficients like:
$$\frac{x^3+x^2}{(2-x)(2+x)}=\frac{A}{2-x}+\frac{B}{2+x}\iff x^3+x^2=A(2+x)+B(2-x)$$
What am I doing wrong?

Hint :
$\dfrac{x^3+x^2}{(2-x)(2+x)}=-x-1+\dfrac{A}{2-x}+\dfrac{B}{2+x}$
