\chapter{Functions and graphs}
\section{Description of functions I}
Answer the questions in your own words.
\begin{enumerate}
\item
What is a function?
\item
What is the domain of a function?
\item
What is the range of a function?
\item What is the name of the variable used for the input values of a function?
\item
What is the name of the variable used for the output values of a function?
\item
How can we decide if an equation in two variables defines one variable as a function of the other?
\end{enumerate}