120/(x-y)+120/(x+y)=160/y 怎样化简成x＝2y和x＝-1/2y

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 [x(x-y)-y(x-y)+(x+y)(x-y)]÷2x其中x=2012 y=2013 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 已知4x=9y求(1)x+y/y (2)y-x/2x {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (1)(x+y)^2-(x-y)^2 y'-2y=(e^x)-x