已知|2x-4|+3x+2y+2|=0则x-y=( ),

已知x*x+4x+y*y-2y+5=0,则x*x+y*y=? 已知3x^2+xy-2y^2=0,求{(x+y)/(x-y)+4xy/(y^2-x^2)}/{(x+3y)*(x-y)} 已知X-Y/X+Y=3,求代数式2(x-y)/X+Y-3X+Y/X+Y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x*x-4xy+4y*y=0 求[2x(x+y)-y(x+y)]/(4x*x-4xy+y*y)的值? 已知x-2y/2x+3y=3/4,则x：y= 已知x²+4x+y²-2y+5=0,则x+y= 已知x,y为实数,根号3x+4 +y^2-6Y+9=0则x+y=? 已知4x-2y=0,求x-y/3x+2y的值 已知x,y>0 2x+y+3=xy 求5x+4y最小值 已知x-y-3绝对值+(2x+2y+10)的平方=0,则(x+y)(x-Y)= 已知x=1/3,y=-1/2,求代数式x-(x+y)+(x+2y)-(x+3y)+(x+4y)-(x+5y)+...-(