Answer
$(8n+3)(8n-3)$
Work Step by Step
The expressions $
64n^2
$ and $
9
$ are both perfect squares (the square root is exact) and are separated by a minus sign. Hence, $
64n^2-9
,$ is a difference of $2$ squares. Using the factoring of the difference of $2$ squares which is given by $a^2-b^2=(a+b)(a-b),$ the expression above is equivalent to
\begin{array}{l}\require{cancel}
(8n)^2-(3)^2
\\\\=
(8n+3)(8n-3)
.\end{array}
