x3-3x2+x+1=0怎么变成(x-1)(x2-2x-1)=0

题目

x3-3x2+x+1=0怎么变成(x-1)(x2-2x-1)=0
请尽快回答

答案

(x³-x²)-(x²-x)-(x²-1)=0
x²(x-1)-x(x-1)-(x+1)(x-1)=0
(x-1)(x²-x-x-1)=0
(x-1)(x²-2x-1)=0