(x-y)的三次方×(x-y)的六次方等于多少
问题描述：
(x-y)的三次方×(x-y)的六次方等于多少
答
解
(x-y)³×(x-y)^6
=(x-y)^(3+6)
=(x-y)^9
(x-y)^9是(x-y)的九次方