Chapter 6 - Factoring, Solving Equations, and Problem Solving - 6.2 - Factoring the Difference of Two Squares - Problem Set 6.2 - Page 249: 99

$(4+x)(16-4x+x^2)$

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, $ 64+x^3 ,$ is \begin{array}{l}\require{cancel} (4+x)[(4)^2-4(x)+(x)^2] \\\\= (4+x)(16-4x+x^2) .\end{array}