Answer
$3(3x-1)(3x+1)$
Work Step by Step
First, we take a common monomial factor as follows
$$
27x^2-3=3(9x^2-1)
.$$
This is a difference between two squares, and hence
$$
(9x^2-1)=(3x-1)(3x+1)
.$$
One can check as follows
$$
3(3x-1)(3x+1)=3(9x-3x+3x-1)=3(9x^2-1)=27x^2-3
.$$
