Chapter 5 - Section 5.7 - Factoring by Special Products - Exercise Set - Page 309: 31

$(p+5q)(p^2-5pq+25q^2)$

Using $a^3\pm b^3=(a\pm b)(a^2\mp ab+b^2)$, or the factoring of the sum/difference of two cubes, then, \begin{array}{l} p^3+125q^3 \\= (p+5q)[(p)^2-(p)(5q)+(5q)^2) \\= (p+5q)(p^2-5pq+25q^2) .\end{array}