已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(x-y

已知x²+y²+5=2x+4y,求【2x²-(x-y)(x-y)】【(x+y-1)(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=2,求2x(x+y)-y(x+y)/4x²-4xy+y² 已知x²+y²-2x+4y+5=0,求x+y 已知x² +y²+5/4=2x+y,求y-x的值 已知x²+4x+y-2y+5=0求x+2y 已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(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)+...-( 若|x+2y-1|+y²+4y+4=0,求（2x-y）²-2（2x-y)(x+2y)+(x+2y)& (2x-y)²-4(x-y)(x+2y) 化简：（2x-y)²-4(x-y)(x+y)