4.2 Relations and Functions
A relation is any set of ordered pairs.
x
y
3
-4
-5
2
-7
-4
-5
7
A function is a relation in which each input has exactly one output
The domain of the function is the set of all input values.
The range of the function is the set of all output values.
You can determine if a relation is a function by checking the table:
x
y
3
-4
-5
2
-7
-4
-5
7
You can determine if a relation is a function by looking at the graph:
** A relation is a function if no vertical line passes through
two or more points on the graph.
Does the graph represent a function?
You can determine whether a relation is a function by mapping:
domain
4
domain
2
3
4
5
range
domain
range
6
5
7
6
5
7
4
range
-1
7
5
domain
2
3
2
5
range
-6
2
-8
7
Give the domain and range of each relation.
Tell whether it is a function.
-3
12
-2
13
-1
14
0
15
4
2
2
4
Express each relation as a table, as a
graph, and as a mapping diagram.
{(-3, 4), (-3, 6), (-1, 7), (0, -2), (4, 6)}