$\"\"$

The polynomial is $\"\"$ .

To find the coefficients of the x-terms, the product of $\"\"$ or $\"\"$ , and a sum of 12.

The two coefficients must be 21 and $\"\"$ since $\"\"$ .

$\"\"$ (Substitute 21x $\"\"$ x for 12x)

$\"\"$

$\"\"$ $\"\"$

The factor of the polynomial is $\"\"$ .