若x+y=-3 3x-3y=

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 （x+y-5)*（x+y-5)+（x-y+3)=0 x*x-y*y 已知:3x-5y=0,求x/y,x-y/y,x-y/x 若(x-y)/(x+y)=3 则(x+2y)/(6x-7y)等于 推倒公式:(x+y)(x*x-3x+y*y)=x*x*x+y*y*y怎么做. 若x,y为正整数,且满足3x(x+y)-y(x+y)=7,求x,y 若2x=3y,则(x*x+y*y)/x*x=? 若x:y=3则x:(x+y)= (x+y)(x-y)+(x-y)平方-(x-y)(3x-y) 其中x=-2 y=3分之一 (x-y) (x-2y)+(x+2y) (x-3y)-2(x-3y) (x-4y)= 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 化简 x-y/(y-x)^3= (x+y)(2x-3y)=? 若3x=5y,则x:y=________,(x-y):y=______ y(x+y)+(x-y)²-（x+y）（x-y）,其中x=-1/3,y=3 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 【2(x-y)^3-8(x-y)^2(x+y)+6y(x-y)^2】/2(x-y)^2= 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值