  In this article, we will showcase some analytical concepts that can be used
to tackle Functional Equations (FE) in the positive real numbers domain. Such
concepts and related techniques have occasionally appeared in recent High
School Math Olympiads, and they are often accompanied neatly by other known
techniques. In each section, we develop a theoretical background; next, we
briefly mention methods that employ the theory and conclude the article by
providing unsolved problems that the reader can try independently.
