1.已知x+y+2(-y-x+1)=3(1-y-x)-4(y+x-1),则x+y=
1.已知1/x+1/y=-1/x+y,则y/x+x/y=?
已知4x=9y求(1)x+y/y (2)y-x/2x
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
1.已知x-1/x+2=y-3/y-4,若用含x的代数式表示y,则y=
{3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y
已知:3x=8y.求(1)x+y/y (2)2x+3y/x-2y
已知x+y+2(-x-y+1)=3(1-y-x)-4(y+x-1),则x+y等于( )
已知正实数x,y满足x+2y=4,则1x+1y
已知3x-4y/2x+y=1/2 求x/y的值
已知X和Y满足3X+4Y=2,X-Y-1/7
先化简再求值(x-y)(x+y)-(x-2y) 的完全平方+x(3x-5y)-(x-y)(x-2y),其中x=1/2 y