已知x+y=a,试求(x+y)3(2x+2y)3(3x+3y)3的值.

问题描述:

已知x+y=a,试求(x+y)3(2x+2y)3(3x+3y)3的值.

(x+y)3(2x+2y)3(3x+3y)3
=(x+y)3[2(x+y)]3[3(x+y)]3
=(x+y)3•8(x+y)3•27(x+y)3
=216(x+y)9
=216a9