Finding the asymptotes of an odd function The question gave the graph shown below, giving one asymptote as $y=f(x)=\frac{1}{2}x - 3$. Graph: 
I was asked to complete the rest of the graph and draw on any missing asymptotes, and this is what I drew: 

For the other asymptote which I drew I wasn't sure what its equation was but I predict it's $y=\frac{1}{2}x + 3$. My question is how would I know for sure that that is the equation of the second asymptote without just guessing?

$$ y= x/2 +3$$
for an odd function
$$ x\rightarrow -x , \, y\rightarrow -y  $$ 
$$ -y= -x/2 +3$$
or 
$$ y= x/2 -3$$
