若｜x｜=2.5,｜y｜=7/3,求x+y.

若x+7y=y-3x，求x 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 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) 若实数X,Y同时满足3x+2y=7和2x+3y=3,求x+y/x-y 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 若x-y/x+y=5,求x-y/2x+2y+5x+5y/3x-3y的值 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 若x-y=1,求代数式x(x-y)+y(y-x)+2013的值 已知|3x-y|+|x+y|=0,求x-y除以x*y的值. 求x:y:z x:y=7/5:7/3,y:x=7:8 若x+y=1,x²+y²=3,求x^3+y^3