已知x+2y=0(x≠0),求分式x²-xy分之2xy+y²的值

已知x+2y=0(x≠0),求分式x²-xy分之2xy+y²的值
已知x+2y=0(x≠0),求分式x²-xy分之2xy+y²的值

已知x+2y=0(x≠0),求分式x²-xy分之2xy+y²的值
x+2y=0
x=-2y
(2xy+y²)/(x²-xy)
=y(2x+y)/[x(x-y)]
=y(-4y+y)/[-2y(-3y)]
=-3y²/6y²
=-1/2

由x+2y=0得x=-2y，x²-xy分之2xy+y²可化简为6y²分之-3y²，最终结果得-2分之1