Answer
$3*(x^2-14x+21)$
Work Step by Step
$3x^2-42x+63$
$3*(x^2-14x+21)$
Factors of 21: 1 and 21, 3 and 7, -1 and -21, -3 and -7
Factors of 1: 1 and 1, -1 and -1
Since there are no two numbers whose sum is -14 and product is 21, we will leave the polynomial alone.
