积分x^2 / (1-x^2)
问题描述：
积分x^2 / (1-x^2)
答
答：
∫[x^2/(1-x^2)]dx
=∫[(x^2-1+1)/(1-x^2)]dx
=∫[-1+1/(1-x^2)]dx
=∫[-1+(1/2)/(1-x)+(1/2)/(1+x)]dx
=-x-(1/2)ln|1-x|+(1/2)ln|1+x|+C
=(1/2)ln[(1+x)/(1-x)]-x+C