已知：x+9y=y-3x,求(x^2-y^2)/(x^2+y^2)的值RT

已知x-y/x+y=3,求代数式5(x-y)/x+y-x+y/2(x-y) 已知x-y=3,求[（x+y)(x-y)-(x-y)^2+2y(x-y)]除以的值 已知3x =2y 求x/x+y+y/x-y-y²/x²-y² 已知:3x-5y=0,求x/y,x-y/y,x-y/x 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知2x-y/x+2y=3,求2(2x-y)/x+2y-9(x+2y)/2x-y+3的值. 已知,X:Y=3:2,求代数式4X-9Y:2X+3Y 已知x/y=3/2求代数式4x-9y/2x+3y 已知2y-x=-3,求[4y(2x-y)-2x(2x-y)]/(2x-y 已知：x+9y=y-3x,求(x^2-y^2)/(x^2+y^2)的值RT 已知：2x+y=6,x-3y=1 求7y(x-3y)(x-3y)-2(3y-x)(3y-x) 已知x-y=1,求[(x+2y)^2+(2x+y)(x-4y)-3(x+y)(x-y)]除以y的值大神们帮帮忙 已知x-y=1,求[(x+2y)²+(2x+y)(x-4y)-3(x+y)(x-y)]÷y的值 已知(x+2y)(2x-3y)=y(y-4x),试求x/y的值 已知x=3分之一,y=-2分之一,求代数式x-(x+y)+(x+2Y)-(x+3y)+(x+4y)...-(x+2009y) 已知x-3y=0,求(2x+y)/(x^2-2xy+y^2)X(x-y) 已知x≠y,x^2-x=y^2-y,求x+y的值. 已知|3x-y|+|x+y|=0,求x-y除以x*y的值.