已知1/x-1/y=2,求分式-x-xy+y/3x+xy-3y的值已知x^2/x^2-2=1/1-a,求(1/1-x - 1/1+x)除以(x/x^2-1 +x)的值(用a表示)

已知1/x-1/y=3,求分式(2x+3xy-2y)/(x-2xy-y) 已知1/x-1/y=5,求分式y+xy-x/2x+7xy-2y的值. 已知1/x-1/y=5 求分式-x+xy+y/2x+7xy-2y 已知1/X-1/y=5,求分式(y+xy-x)/(2x+7xy-2y)的值 已知1/x-1/y=5,求分式2x+5xy-2y/3x-xy-3y 已知1/x+1/y=3,求分式3x-2xy+3y/x+xy+y的值 已知,1/x+1/y=5.,求分式3x+xy+3y/x-2xy+y的值 已知1/x-1/y=2001,求分式x-xy-y/x-y的值 解一道分式题已知1/x-1/y=3 求分式(4x-5xy-4y)/(3x-2xy-3y)的值. 已知1/x-1/y=5、求分式3x+5xy-3y/y-xy-x的值 已知1/x-1/y=3,求分式3x-xy+3y/x+xy+y的值. 已知1/x -1/y=3,求分式3x+3xy-3y求分式(3x+3xy-3y)/(x-2xy-y)的值~ 已知x+2y=0,求分式2xy+y^2/x^2-xy 已知x-y/xy=3,求分式2x+3xy-2y/x-2xy-y的值. 已知x-y=3xy,求分式3x+2xy-3y/x-2xy-y的值 已知1/x-1/2y=1/3,求分式(2x+3xy-4y)/(x-3xy-2y)的值 已知x^2+y^2-6x-8y+25=0,求分式1/xy的值 已知1/x-1/y=3,求分式2x+3xy-2y/x-2xy-y的值