How can one determine if an equation is linear or nonlinear

When trying to classify an equation as linear or nonlinear, it is important to examine the structure of the equation. For example, if we look at the equation y = 2x + 1, we can see that the highest degree of the equation is one. This indicates that the equation is linear in nature. Conversely, a nonlinear equation will not follow this format and will have a different structure altogether.