已知2x+y/2=5x+2y/4=1求x+2y+1/2x-5y+7
已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(
已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y
已知4x=9y求(1)x+y/y (2)y-x/2x
已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y)
已知x²+y²+5=2x+4y,求代数式(2x²-(x+y)(x-y))x((x+y-1)
已知x+y=-1,xy=-2,求代数式-5(x+y)+(x-y)+x(xy+y)的值
已知x^2+4y^2-4x+4y+5=0,求(y^4-x^4)/(y-2x)(x+y)*2x-y
已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y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^2+y^2+5=2x+4y,求代数式[2x^2-(x+y)(x-y)][(x+y-1)(x-y+1)+1-2y]
已知x*x+4x+y*y-2y+5=0,则x*x+y*y=?
已知:3x=8y.求(1)x+y/y (2)2x+3y/x-2y