=(x-1)^2*(x+1)^2*(x+1) (x^2-1)^2*(x+1) (x^4 - 2x^2+1)*(x+1) x^5-2x^3+x+x^4 - 2x^2+1求导得 5x^4+4x^3-6x^2-4x+1
f(x)=(x+1)^-1-4(x+1)^-2+4(x+1)^-3f(x)'=-(x-1)(x-5)/(x+1)^4
看不清
