1.(xy-1)^2-(x+y-2xy)(2-x-y)

问题描述:

1.(xy-1)^2-(x+y-2xy)(2-x-y)
2.(x+y)(x+y+2xy)+(xy-1)(xy+1)

(1) (x-1)^2 (y-1)^2
(2) (1 + x) (1 + y) (-1 + x + y + x y)