1.（2x-y+1)(y-1+2x)

1、x(x-y)(x+y)-x(x+y)^2 (1)(x^2/x)-y-x-y [(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y (1)(x+y)^2-(x-y)^2 1、(x-2y)(x+y) 1) (2x+5y)(2x-5y)(-4x^2-25y^2) 2) [（x+y)(x-y)-(x-y)^2+2y(x-y 因式分解 (1)6(x-y)^3-3y(y-x)^2 (2)x(x-y)(a-b)-y(y-x)( 先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y (3x-y)^2+(3x+y)(3x-y),x=1,y=-2 （x+2)(x+3) (x-4)(x+1) (y+4)(y-2) (y-5)(y-3) 已知4x=9y求(1)x+y/y (2)y-x/2x 1 4(x-y+1)+y(y-2x)