x^2-xy-4+2y因式分解
问题描述：
x^2-xy-4+2y因式分解
答
x^2-xy-4+2y因式分解
= x^2-4+2y-xy
= (x+2) (x-2)+ y ( 2-x)
= (x+2) (x-2)- y (x-2)
= (x-y+2 ) (x-2 )