2x-y)^2-(x-y)^2 =(2x-y+x-y)(2x-y-x+y) =3x(3x-2y)最后一步怎么理解

x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 化简y(x+y)+(x+y)(x-y)-x^2 因式分解x(x+y)(x-y)-x(x+y)^2 (x+y)(x-y)-(x-y)^2如题 (x+y)(x-y)-(x-y)^2 【2(x-y)(x-y)(x-y)-8(x-y)(x-y)(x+y)+6y(x-y)(x-y)]/2(x-y)(x-y) 填空：x-y/x+y=( )/x^2-y^2 （x-y)2•(y-x)³(x-y)=? (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) x^2(x-y)+(y-x) x(x-y)2-(y-x)3 (x-4y)(2x+y)= (x+y)(2x-3y)=? x+y>=2,x-y x+y>=2,x-y y'-2y=(e^x)-x y'+2y/x=x通解