Answer
$ f(x)$ is odd.
Work Step by Step
$ f(x)$ is odd if $f(-x)=-f(x)$
$ f(x)$ is even if $f(-x)=f(x)$
-------------
$f(x)=\displaystyle \frac{x}{x^{2}-9}$
$f(-x)=\displaystyle \frac{-x}{(-x)^{2}-9}=-\frac{x}{x^{2}-9}$
$=-f(x)$
$ f(x)$ is odd.