Since f (x) = x does not fit the definition of a linear function, nor is it a linear equation,
it is simply defined as the absolute value function.
Often one hears that mathematics is a science of definition. Evidently, the definition
required by the two strict conditions clearly helps one determine whether an equation is a linear
function or not. As a math student, one always finds that a specific definition must be well
orchestrated with properties, subsequent theorems and its impact on other area of mathematics.
Here, I wonder how the more precise definition helps mathematicians in the study of linear
algebra. I need to wait till college to witness it though, I am just curious.