Question

what is the greatest common factor of 12a and 9a²?
○ 9
○ 36
○ 3a
○ 12a²

Explanation:

Step1: Factor coefficients

Factor 12 and 9:
$12 = 2\times2\times3$, $9 = 3\times3$.
GCF of 12 and 9 is 3.

Step2: Factor variables

For $a$ (from $12a$) and $a^2$ (from $9a^2$), the lowest power of $a$ is $a^1$.

Step3: Combine GCFs

Multiply coefficient GCF (3) and variable GCF ($a$): $3\times a = 3a$.

Answer:

3a (corresponding to the option "3a")