f'(sin^2x)=1-2sin^2x+sin^2x/(1-sin^2x) f'(x)=1-2x+x/(1-x) f(x)=∫[1-2x+x/(1-x)]dx =x-x^2+∫x/(1-x)dx =x-x^2-∫-x/(1-x)dx =x-x^2-∫[1+1/(x-1)]dx =x-x^2-x-ln(1-x)+C =-x^2-ln(1-x)+C 追问: =x-x^2-∫[1+1/(x-1)]dx =x-x^2-x-ln(1-x)+C ln(1-x)的ln前是不是应该是+,为什么是-?