一道数学题因式分解:

问题描述:

一道数学题因式分解:

x(y+1)+y-1或y(x+1)+x-1

(X+1)(Y+1)

(1-x^2)(1-y^2)-4xy
=1-x^2-y^2+x^2y^2 -- -- -- -- ^2代表平方
=(-x^2-y^2-2xy)+(x^2y^2-2xy+1)
= -(x+y)^2+(xy-1)^2
= (xy-1+x+y) (xy-1-x-y)

xy+1+x+y
=x(y+1)+(y+1)=(y+1)(x+1)