1/2(x+y)^5+2(x+y)^2-4/3(x+y)^3-1/2(x+y)^5+1/3(x+y)^3,其中x=3-y

[(-x-y)(-x+y)-(x+y)^2-x(y-y^2)}÷1/2y (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) {6(x-y)-7(x+y)=21 {2(x-y)-5(x+y)=-1 x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 化简y(x+y)+(x+y)(x-y)-x^2 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 5x(x-y)+2y(x-y) 化简:5(x-y)+2(x+y)-3(x-y) 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) (x+y)(x-y)-(x-y)^2如题 (x+y)(x-y)-(x-y)^2 1、y-x/x²-y²2、(x-y)(y-z)(z-x)/(z-y)(y-x)(x-z) 分式的加减:[(x/y-y/x)除以（x+y）+x（1/y-1/x)]除以1+x/y,其中x=5,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) 绝对值化简|x-y+1|-2|y-x-3|+|y-x|+5y （X+2Y)(5X-2Y) (x+2y)(5x-2y) 4x+2y-5x-y