题目

分解因式:①(x+y)^2+4(x-y)^2-4(x^2-y^2)；②x^2-9y^2+4z^2+4xz；③(x+y)^2-4xy；④x^2-1-2xa+a^2

提问时间：2021-02-19

答案

:①(x+y)^2+4(x-y)^2-4(x^2-y^2)；
=(x+y)²-4(x+y)(x-y)+4(x-y)²
=(x+y-2x+2y)²
=(3y-x)²
②x^2-9y^2+4z^2+4xz
=(x+2z)²-9y²
=(x+2z+3y)(x+2z-3y)
③(x+y)^2-4xy
=x²+y²-2xy
=(x-y)²
④x^2-1-2xa+a^2
=(x-a)²-1
=(x-a+1)(x-a-1)