4+12(x-y)+9(x-y)^2

问题描述:

4+12(x-y)+9(x-y)^2
分解因式的
thanks..

4+12(x-y)+9(x-y)^2
=2^2+2*2*[3(x-y)]+[3(x-y)]^2
=[2+3(x-y)]^2
=(3x-3y+2)^2