Answer
$\left( x+\dfrac{1}{3} \right)\left( x^2-\dfrac{1}{3}x+\dfrac{1}{9} \right)$
Work Step by Step
Using $a^3+b^3=(a+b)(a^2-ab+b^2)$ or the factoring of 2 cubes, the factored form of the given expression, $
x^3+\dfrac{1}{27}
,$ is
\begin{array}{l}
\left( x+\dfrac{1}{3} \right)\left[ (x)^2-(x)\left( \dfrac{1}{3} \right)+\left( \dfrac{1}{3} \right)^2 \right]
\\\\=
\left( x+\dfrac{1}{3} \right)\left( x^2-\dfrac{1}{3}x+\dfrac{1}{9} \right)
.\end{array}