Answer
$(3x+1)(3x-1)$
Work Step by Step
$9x^2-1$
To factor the difference of two squares, we can refer to the general form that any difference of two squares can be written as, that is:
$(x^2-a^2)=(x+a)(x-a)$
Therefore, the answer can be written as:
$(3x+1)(3x-1)$
