x^2+y^2+/y^2-3xy+2/=2xy
x^2-2xy+y^2+/y^2-3xy+2/=0
(x-y)^2+/y^2-3xy+2/=0
x-y=0且y^2-3xy+2=0
x-y=0---->x=y
y^2-3xy+2=y^2-3y^2+2=-2y^2+2=0---->y=±1
所以,x=y=±1时,等式x^2+y^2+/y^2-3xy+2/=2xy成立