Answer
$(2a+1)(4a^2-2a+1)$
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, $
8a^3+1
,$ is
\begin{array}{l}
(2a+1)[(2a)^2-(2a)(1)+(1)^2]
\\\\=
(2a+1)(4a^2-2a+1)
.\end{array}