### Introduction

In this Section we examine more terminology associated with functions. We explain one-to-one and many-to-one functions and show how the rule associated with certain functions can be reversed to give so-called inverse functions. These ideas will be needed when we deal with particular functions in later Sections.

#### Prerequisites

- understand what is meant by a function
- be able to sketch graphs of simple functions

#### Learning Outcomes

- explain what is meant by a one-to-one function
- explain what is meant by a many-to-one function
- explain what is meant by an inverse function, and determine when and how such a function can be found