## Algebra 1: Common Core (15th Edition)

$3x$.
List the prime factors of each term. Identify the factors common to all terms. $3x^{4}=(3)\cdot[x]\cdot x\cdot x\cdot x$ $9x^{2}=(3)\cdot 3\cdot[x]\cdot x$ $12x=2\cdot 2\cdot(3)\cdot[x]$ GCF=$(3)\cdot[x]$, or $3x$.