若(1/x )-(1/y)=3,求(3x+4xy-3y)/(x-2xy-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 (x-y)/(x+y)=3求( 3x-2y-1)/(x+y-5) 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 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 {(x+y)/2+(x-y)/3=1,(x+y)-5(x-y)=2.求x=?,y=? 若x、y满足2x+y=6,x-3y=1,求7y(x-3y)²-2(3y-x)³的值 (-x+6):(x-y);(4x+y)=3;14:1,求x+y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(2x-y-1)²+|x-2y-3|=0,求代数式(2x+y)(2x-y)-(x+2y)(x-2y-1)的值 求值域 y=|x-1|-|3+x| 求值域y=|x-1|-|3+x| 求y=x（1-3x） (x y=(X+1)(X+2)(X+3)求导数 已知x(x-1)-(x²+y)=3 求x(x-y)+(y-x)的值 若x^5+x^4y+x^4+x+y+1=0,且3x+2y=1,求x,y的值 y=(2x*x-2x+3)/(x*x-x+1),求值域? 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x)