已知x-2y=0,求y/（x^2-y^2）除以1/（x-y）的值

已知X*X+Y*Y+6X-8Y+25=0 求（Y/X)+(X/Y)-2=? 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-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x≠y,x^2-x=y^2-y,求x+y的值. 已知|x|=2,|y|=3,|x+y|=-(x+y)求x-y 已知x-3y=0,求(2x+y)/(x^2-2xy+y^2)X(x-y) 已知x-y/x=x/x-2y（y不等于0）,求x：y的值 已知x-y/x=x/x-2y(y不等于0),求x：y的值 已知x^2+y^2+13-4x+6y=0,求(2x-y)^2-2(2x-y)(x+2y)+(x+2y)^2 已知：x^2/(z+y)+y^2/(x+z)+z^2/(x+y)=0,求x/(z+y)+y/(x+z)+z/(x+y)的值. 已知X.x+y.y-4x+2y+5=0,求4X.X-12X Y+9Y.y的值 已知x+y=a,2x-y=-2a,求[（x/y-y/x)/(x+y)-x(1/x-1/y)]/[(x+1)/y]的值 已知(2x+1)*2+y*2+2y+1=0 求{(x*2+y*2)-(x-y)*2+2y(x-y)}/(2y) 已知x^2+2x+y^2-6y+10=0 求（x+y)^2 已知：x^2+y^2+4x-6y+13=0,求x^y值. 已知(x-y)^2+|5x-7y-2|=0,求x,y的值.