f(x)=(x-1)(x+1)³f'(x)=(x+1)³+3(x+1)²(x-1) =(x+1)²(x+1+3x-3) =(x+1)²(4x-2)
后面是三次方吧？=(x+1)^3+3(x-1)(x+1)^2
4X^3+6X^2-2
