∫ dx/x^2(1-x^2)
=∫1/x^2 dx +∫ 1/(1-x^2) dx
= -1/x + 0.5*∫ 1/(1-x) +1/(1+x) dx
= -1/x -0.5ln|1-x| +0.5ln|1+x| +C,C为常数