Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$\dfrac{1}{3}(3x+1)(3x-1)$
Factoring $\dfrac{1}{3}$, the given expression, $3x^2-\dfrac{1}{3} ,$ is equivalent to \begin{array}{l} \dfrac{1}{3}(9x^2-1) .\end{array} Using $x^2-y^2=(x+y)(x-y)$ or the factoring of the difference of 2 squares, then the factored form of the expression, $\dfrac{1}{3}(9x^2-1) ,$ is \begin{array}{l} \dfrac{1}{3}(3x+1)(3x-1) .\end{array}