## Elementary and Intermediate Algebra: Concepts & Applications (6th Edition)

$x=\left\{ -9,-2 \right\}$
Factoring the given equation, $n^2+11n+18=0 ,$ results to \begin{array}{l}\require{cancel} (n+9)(n+2)=0 .\end{array} Equating each factor to zero (Zero Product Principle), then the solutions to the equation, $(n+9)(n+2)=0 ,$ is \begin{array}{l}\require{cancel} n+9=0 \\\\ n=-9 ,\\\\\text{OR}\\\\ n+2=0 \\\\ n=-2 .\end{array} Hence, $x=\left\{ -9,-2 \right\} .$