# Functions

Functions are used throughout calculus to model different quantities like cost, revenue, and profit. We need to review the basic concepts around functions before we can examine limits and other calculus concepts.

We start by examining the role of independent and dependent variables. Once we understand variables, we can use them to define functions.

**Read **in Section 10.1

- What is a function?
- What is function notation?
- Handout: Use Function Notation
- What is a piecewise defined function?

**Watch** Video Playlist