已知2X-3Y=-8,2Y-3X=7,则X=...Y=...

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) 已知实数x.y满足根号(x+y-8)+根号(8-x-y)=根号(3x-y-4)+根号(x-2y+7),求x,y 已知｛3x+2y=3 2x+3y=7 ,则x+y= ,x-y= 已知：3x=8y.求（1）x+y/y (2)2x+3y/x-2y 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知1/x-1/y=3,则代数式x(2-7y)-y(7x+2)/x(1-y)-y(x+1)的值为多少. 已知xy/x+y=2,则代数式3x-5y+8y/-x+3xy-y的值 已知x-2y/2x+3y=3/4,则x：y= 已知x-2y=3,则(2x+y-6)/(3x-y-9)=? 已知方程组{2x+y=7,x+2y=8,则x-y=(),x+y=().