ABSTRACT
It can happen that although a function does not have a limit as x0/c in the sense of Section 14, it does have a limit in a more restricted sense when x
approaches c from one side or the other. Such limits are called one-sided
limits, and although a one-sided limit may exist when x approaches c from
one direction, there may or may not be another one-sided limit when it
approaches c from the other direction.