Answer
$3a^{2}$
Work Step by Step
To find the GCF:
First, list all the factors.
Then, multiply the factors all the numbers have in common. That is the GCF.
3 $\times$ 2 $\times$ a $\times$ a $\times$ a $\times$ a
3 $\times$ a $\times$ a $\times$ a $\times$ a $\times$ a
3 $\times$ 5 $\times$ a $\times$ a
3 $\times$ a $\times$ a = $3a^{2}$
