**Families of Functions**

When we wish to describe a particular function, we specify its input-output rule. We can do this in a number of ways. For example, if we wish to describe the volume of water in our bathtub, we might:

"The volume starts (when |

**V(t) = 0 + (0.5)t**

Each of these descriptions is a **representation** of the function that we are trying to model.