化简x(y-x)-y(x-y)

{(x,y) |x|+|y| x>y?x:y 化简:(x-3y)(x+y)-(x-2y)(x+2y)-(x-y)平方 化简：（2x-y)²-4(x-y)(x+y) (x+y) X、Y 1.(x-y)(x+y)+(x-y)+(x+y) |x|+|y| x y x+yy x+y xx+y x y 1 ,化简 （x-y)(x+y) 1、x(x-y)(x+y)-x(x+y)^2 z/(x-y) × y/(x+y)