y=(x-1)^2*(x+1)
y'=(x-1)^2*(x+1)'+((x-1)^2)' * (x+1)
=(x-1)^2+2(x-1)(x+1)
=(x-1)(x-1+2x+2)
=(x-1)(3x+1)
=3x^2-2x-1
或者先展开：
y=(x-1)^2(x+1)
=(x-1)(x^2-1)
=x^3-x^2-x+1
y'=3x^2-2x-1