Answer
See image.
.
Work Step by Step
Equate $f(x,y)=c$
for each value of c
$ xy=c\quad$or
For $c=0, $ we have the origin.
For the other values of c,
$y=\displaystyle \frac{c}{x}$
is a family of hyperbolas related to $y=\displaystyle \frac{1}{x}$, by performing reflections about the x-axis
and vertical stretching.
