分式题一道,

问题描述:

分式题一道,
已知2x-3y=0,则分式(x^2+y^2)/(x^2-3xy)的值是?

(x^2+y^2)/(x^2-3xy)
=(x^2+4x^2/9)/(x^2-2x^2)
=-(1+4/9)
=13/9