(a+b)^2n-1*(-a-b)^4+(a+b)^(n+1)*(a+b)^(n+2)

问题描述:

(a+b)^2n-1*(-a-b)^4+(a+b)^(n+1)*(a+b)^(n+2)

(a+b)^2n-1*(-a-b)^4+(a+b)^(n+1)*(a+b)^(n+2)
=(a+b)^2n-1*(a+b)^4+(a+b)^(n+1)*(a+b)^(n+2)
=(a+b)^(2n+3)+(a+b)^(2n+3)
=2*=(a+b)^(2n+3)最后一步什么意思合并同类项2*?=2*(a+b)^(2n+3)