Chapter 6 - Factoring, Solving Equations, and Problem Solving - 6.2 - Factoring the Difference of Two Squares - Problem Set 6.2 - Page 249: 92

$(x+2y)(x^2-2xy+4y^2)$

Using $a^3+b^3=(a+b)(a^2-ab+b^2)$, or the factoring of the sum of $2$ cubes, the factored form of the given expression, $ x^3+8y^3 ,$ is \begin{array}{l}\require{cancel} (x+2y)[(x)^2-x(2y)+(2y)^2] \\\\= (x+2y)(x^2-2xy+4y^2) .\end{array}