Question

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

Explanation:

Step1: Factor coefficients and variables

For $12a$: $12a = 2^2 \times 3 \times a^1$
For $9a^2$: $9a^2 = 3^2 \times a^2$

Step2: Find common lowest powers

Common coefficient factor: $3$ (lowest power of 3)
Common variable factor: $a^1 = a$ (lowest power of $a$)

Step3: Multiply common factors

$\text{GCF} = 3 \times a = 3a$

Answer:

C. 3a