因式分解:9(x-2y)^2-12(x-2y)+4
问题描述：
因式分解:9(x-2y)^2-12(x-2y)+4
答
9(x-2y)^2-12(x-2y)+4
= [3(x-2y)]^2 - 2* [3(x-2y)] *2 + 2^2
= [3(x-2y) -2] ^2
=(3x-6y-2)^2