Answer
$n(n+3)(n-3)$.
Work Step by Step
The given polynomial is
$= n^3-9n$
Factor out $n$.
$= n(n^2-9)$
Write the the polynomial as $a^2-b^2$.
$= n(n^2-3^2)$
Use difference of two square pattern
$a^2-b^2=(a+b)(a-b)$.
We have $a=n$ and $b=3$.
$= n(n+3)(n-3)$
Hence, the factor of the polynomial is $n(n+3)(n-3)$.
