is a function ofThis way of representing the dependent variable is called function notation. A function can be represented using a table, a mapping diagram, an equation, or a graph.
Note that every function is a relation, but not every relation is a function. In the applet below, Relation I is a function because each input value in the domain is paired with only one output value in the range. However, Relation II is not a function because is paired with two output values in the range.
There are different ways to determine whether or not a relation is a function. The way the relation is represented can help to decide how to check whether or not it is a function.