(x-y)的三次方*(x-y)的平方*(y-x)
问题描述：
(x-y)的三次方*(x-y)的平方*(y-x)
答
(x-y)^3 * (x-y)^2 * (y-x)
= (x-y)^3 * (x-y)^2 * {-(x-y) }
=- (x-y)^3 * (x-y)^2 * (x-y)
=- (x-y)^6