数学题x^2-2xy+y^2-x+y-2因式分解,
问题描述：
数学题x^2-2xy+y^2-x+y-2因式分解,
答
x²-2xy+y²-x-y-2
=(x-y)²-(x-y)-2
=(x-y-2)(x-y+2)
先是 完全平方,再是十字相乘.