1.[1/2x-y)^2+(1/2x+y)^2](1/2x^2-2y^2) 2.(2x^3-5x-4)(3x^2-7x+8) 简便运算

[(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y 1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) (x-y)(2x-y-1) (x/x+y-x/y-x-2xy/x.x-y.y)/(1/x-1/y) 分式化简 x²/xy-x/y 3x/4x+y - x-2y/4x+y (1-y/y+x)÷x/y²-x² 2y(x+二分之一y)-[(x+y)(x-y)+2y(y+x)],其中|x-1|=2 （x-y)(x+y)-(x+y)^2+2y(y-x),其中x=1,y=3. 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 [(-2x-y)^2-(2x+y)(2x-y)]÷2y-1/2y 1.(x-2y)(x+2y)-(x平方+y)(x平方-y) 2.(2x-y)(y+2x)-(2y+x)(2y-x)3.已知：x+y=6,x平方-y平方=48,求x,y的值4.x平方-2x分之x+2 -- x平方-4x+4分之x-1 1.(x-y)(x+y)+(x-y)+(x+y)2.x(x+2)-(x+1)(x-1),其中x=-二分之一请写清步骤,结果. 求(1+y)-2x(1+y)+x(1-y) [(x/x-y) -1]/(y的平方/x+y)乘以(x-x的平方/x+y),其中x=—2,y=—1. (x-y/1-x+y/1)÷2y/y-x计算错了，是(1/x-y-1/x+y)÷2y/y-x 化简(2x+y)(2x-y)-(x+2y)(x-2y-1) x+2y=2x+y+1=7x-y 求：2x-y? 把4（x-y+1)+y(y-2x)因式分解