(x-y)²-(3x-3xy+y²)因式分解
问题描述：
(x-y)²-(3x-3xy+y²)因式分解
答
(x-y)²-(3x-3xy+y²)
=x²+y²-2xy-3x+3xy-y²
=x²-3x+xy
=x(x+y-3)