Math 8 Identifying Functions Practice Problems
KEY
In the boxes below, (a) state if the image on the left is a function or
non-function and (b) explain/justify your answer. Please use complete sentences.
1. The graph does not represent a function.
The relation (graph) is not a function because the vertical line test shows
that there are inputs with more than one output. For example, the input of
2 has different outputs.
2. The input/output table represents a function.
The relation (input/output table) is a function because each input has
exactly one output.
3. The graph represents a function.
The relation (graph) is a function because the vertical line test shows that each
input has only one output.
{(1,1), (2,4), (3,9), (4,16), (2, 8)}
4.The set of ordered pairs does not represent a function.
The relation (set of ordered pairs) is not a function because the input of 2
has more than one output.
5.The input/output table does not represent a function.
The relation (input/output table) is not a function because the input of 1
has different outputs. OR The relation (input/output table) is not a function
because the input of 4 has different outputs.
{(5,10), (2, 6), (7, 9), (4,4)}
6. The set of ordered pairs represents a function.
The relation (set of ordered pairs) is a function because each input has exactly
one output.
7. The table below represents a function. Fill in the last row (shaded) with values that will turn the relationship into a
non-function. YOU CAN HAVE MULTIPLE ANSWERS AS LONG AS YOU USE ONE OF THE INPUTS AGAIN, BUT GIVE IT A
DIFFERENT OUTPUT. FOR EXAMPLE, (6, 5) OR (4, 9) OR (5, -1) OR (2, 18)
Input
6
4
5
2
Output
10
8
9
6
Explain why the change you made turned the relationship into a non-function.
The change turns the relationship into a non-function because the input of
<whichever input you used goes here> has more than one output.