Answer:
6a
Step-by-step explanation:
The GCF (Greatest Common Factor) is a number/variable that you can take out of all of the terms in the expression.
In this case, each term in this expression has a 6, and an a, but not all have an x, so we only take out:
6a
By taking 6a, you get:
6a([tex]x^2[/tex] + x + 1)