化简2x-(x-y)-y等于

化简2x-(x-y)-y等于 化简y(x+y)+(x+y)(x-y)-x^2 化简3x-2y-(y+3x)-(2x-3y)等于多少 y/2x-y+2x/y-2等于多少 2x+y+4y等于多少 2x*4y等于? (X+Y)^2等于几 化简 (x减y)(x加y)加(x减y)加(x加y)等于 (y/x+x/y+2)除以（y/x+x/y-2)等于多少 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 (x-y)的四次方(x-y)-2(x-y)²(y-x）³等于? 2(x+y)(x-y)-(x+y)²-(x-y)² 等于多少 3y/x*x-y*y+x/x*x-2xy+y*y+6y*y/x*x*x-x*x*y-xy*y+y*y*y等于多少? 1/2X-1/X+Y*(X+Y/2X-X-Y)等于多少, x^2(x+y)^2 等于多少 化简：{2/3x-2/(x+y)[(x+y)/3x-x-y]}/(x+y)/x 化简3x-2/(x+y)[(x+y)/3x-x-y]÷(x-y)/x 化简：[(x+y)(x-y)(x+y)^2-2y(x-2y)](-2y) 谢谢!