#### Answer

$3x(x+7)$

#### Work Step by Step

The greatest common factor of 3 and 21 is $3$.
The greatest common factor of $x^2$ and $x$ is $x$.
Thus, the greatest common factor of the given binomial is $3x$.
Factor out $3x$ to obtain:
$=3x(x+7)$

Published by
Cengage Learning

ISBN 10:
1285194055

ISBN 13:
978-1-28519-405-9

$3x(x+7)$

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