若1/x - 1/y =1 ,求(3y-xy-3x) / (x-xy-y) 的值.

若2/x-1/y=3,求[y/x-y/x-y(x-y/x-x+y)]/x-2y/x的值 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若(-x+6):(x-y):(4x+y)=3:14:1,求x+y 若x-y=1,求代数式x(x-y)+y(y-x)+2013的值 若x*x+y*y=x+y-1/2,求x,y的值如题 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 若x-y=2(x+y),求代数式x-y/x+y+x+y/x-y求代数式 x+y分之x-y+x-y分之x+y 已知:y=ax的3次方+bx+3,当x=-1/2时,y=-7,试求x=1/2时,y的值 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 若x+y=1,x²+y²=3,求x^3+y^3 若x-y=3,x^2-y^2=1,求x+y的值 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 若x＞1,y＞0,且满足 xy=x^y,x/y大于等于x^3y,则y则 最大值求y 的最大值 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 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 若(2x-y-1)2+|x-2y-3|=0,求代数式(2x+y)(2x-y)-(x+2y)(x-2y-1)的值若(2x-y-1)²+|x-2y-3|=0,求代数式(2x+y)(2x-y)-(x+2y)(x-2y-1)的值 若1/x-1/y=2,求(3x-2xy-3y)/(x-2y-y)的值 若x＞1,y＞0 ,且满足xy=x^y,x/y=x^3y,求x+y的值