Chapter 5 - Polynomials and Factoring - 5.7 Solving Quadratic Equations by Factoring - 5.7 Exercise Set - Page 351: 8

$x=\{-5,4\}$

Equating each factor to zero (Zero Product Principle), then the solutions to the given equation, $ (x+5)(x-4)=0 ,$ is \begin{array}{l} x+5=0 \\\\ x=-5 ,\\\\\text{OR}\\\\ x-4=0 \\\\ x=4 .\end{array} Hence, $ x=\{-5,4\} .$