Answer
$3$;
$-\text{ }\text{ } 3x$
Work Step by Step
The given expression can be written as:
$=x^3+3^3$
(a sum of two cubes)
RECALL:
The sum of two cubes, $a^3+b^3$, can be factored as $(a+b)(a^2-ab+b^2)$.
Factor the sum of two cubes using the formula above with $a=x$ and $b=3$ to obtain:
$=(x+3)(x^2-3x+3^2)
\\=(x+3)(x^2-3x+9)$
Thus, the missing expressions in the given statement are:
$3$;
$-\text{ }\text{ } 3x$
