Chapter 2 - Equations, Inequalities, and Problem Solving - 2.1 Solving Equations - 2.1 Exercise Set - Page 86: 16

a solution

Substituting $ x=-1$ to the given equation, $ -4+x=5x $, then \begin{array}{l} -4+(-1)=5(-1) \\\\ -4-1=-5 \\\\ -5=-5 \text{ (TRUE)} .\end{array} Since the solution above ended with a $\text{ TRUE }$ statement, then the given value of the variable is $\text{ a solution }$ to the given equation.