x@y=(x+y)除以2,X#Y=3X-Y除以2 问：(9@x）#30=6,求x的值.

已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 (x-y)^7除以(y-x)^3除以(y-x)^2=_____ 化简,求值：[(x/y)-(y/x)]除以[(x/y)+(y/x)-2]除以[1+(y/x)],其中x=1/2,y=1/3 解方程组3(x+y)-4(x-y)=4,x+y除以2+x-y除以6=1 化简[(3x+4y)^2-(2x+y)(2x-y)+(-x+y)(5x-y)]除以-2y,其中x=-1,y=1 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 化简:【(x-y)的2次方+(x+y)(x-y)】除以2x,其中x=3,y=1.5 已知|3x-y|+|x+y|=0,求x-y除以x*y的值. 函数y=2x+3除以(x-1)(x x-y/x-x+y/y-(x+y)(x-y)/y² y/x=2 已知2x-y/x+3y=2,求代数式4x-2y/x+3y减4x+12y除以2x-y 已知x-y除以x+y=3,求代数式x+y分之2（x-y)-3(x-y)分之x+y的值. 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 (2x+3y)除以(5x-3y)=3/5求x比y [(x+2y)(x-2y)-(x-2y)^2+8y(x+y)]除以4x= 【(x-y)^2+(x+y)(x-y)】除以 2x [(x-y)²+(x+y)(x-y)]除以2x 如果3x除以(x+y)=2 求y除以x的值