(a-b)^n(b-a)^2n(a-b)^5
问题描述：
(a-b)^n(b-a)^2n(a-b)^5
答
(a-b)^n(b-a)^2n(a-b)^5
=(a-b)^n(a-b)^2n(a-b)^5
=(a-b)^(n+2n+5)
=(a-b)^(3n+5)