已知x
问题描述：
已知x
答
作差得
(x³-1)-(2x²-2x)
=(x-1)(x²+x+1)-2x(x-1)
=(x-1)(x²+x+1-2x)
=(x-1)(x²-x+1)
=(x-1)[(x-1/2)²+3/4]
∵x