## Intermediate Algebra (12th Edition)

$\bf{\text{Solution Outline:}}$ A linear function is one where the exponent of all variables is $1.$ The only exception are linear equations of the form $x=a,$ where $a$ is a constant. $\bf{\text{Solution Details:}}$ Among the choices, only $\text{ Choice A }$ is an equation whose variables all have an exponent of $1$. Hence, it is a linear function.