The numerical coefficients of given numerical are 12, 6, 2

Greatest common factor of 12, 6, 2 is 2.

Common literals appearing in given numerical are a and x

Smallest power of x in three monomials = 2

Smallest power of a in three monomials = 1

Monomials of common literals with smallest power= ax²

Hence, the greatest common factor = 2ax²