Determine if Linear y=9x

A linear equation is an equation of a straight line, which means that the degree of a linear equation must be ${\displaystyle 0}$ or ${\displaystyle 1}$ for each of its variables. In this case, the degree of variable ${\displaystyle y}$ is ${\displaystyle 1}$ and the degree of variable ${\displaystyle x}$ is ${\displaystyle 1}$.