#### Answer

$6x$;
$6x$

#### Work Step by Step

RECALL:
A difference of two squares can be factored using the formula:
$a^2-b^2=(a+b)(a-b)$
The given binomial can be written as:
$=(6x)^2-7^2$
This binomial is a difference of two squares.
Factor using the formula above with $a=6x$ and $b=7$ to obtain:
$=(6x+7)(6x-7)$
Thus, the missing expression in the given statement are:
$6x$; $6x$