## Intermediate Algebra (12th Edition)

$(r+7)(r^2-7r+49)$
$\bf{\text{Solution Outline:}}$ To factor the given expression, $r^3+343 ,$ use the factoring of the sum/difference of $2$ cubes. $\bf{\text{Solution Details:}}$ Using $(a\pm b)(a^2\mp ab+b^2)$ or the factoring of the sum/difference of $2$ cubes, the expression above is equivalent to \begin{array}{l}\require{cancel} (r+7)[(r)^2-r(7)+(7)^2] \\\\= (r+7)(r^2-7r+49) .\end{array}