Let's solve each of the
domain and range mapping diagrams to determine whether each depicts a
function or
not.
---
🔍 Definition of a Function:
A
function is a relation where
each input (element in the domain) is paired with
exactly one output (element in the range).
In other words:
-
No element in the domain can map to more than one element in the range.
- But multiple inputs
can map to the
same output.
We’ll go through each diagram one by one.
---
1)
Domain: {2, 6, 7, 8, 9}
Range: {0, 7, 9}
- 2 → 0
- 6 → 7
- 7 → 7
- 8 → 9
- 9 → 9
✔ Each input maps to
only one output.
Even though 7 and 8 both map to 7 and 9 respectively, and multiple inputs go to same outputs — that’s fine.
➡️
Function: YES
---
2)
Domain: {5, 7, 9}
Range: {1, 3, 6, 8}
- 5 → 1
- 5 → 3
- 7 → 6
- 9 → 8
- 9 → 1
✘ 5 maps to both 1 and 3, and
9 maps to both 8 and 1 → multiple outputs for single inputs.
➡️
Function: NO
---
3)
Domain: {1, 3, 6}
Range: {1, 6, 7, 8, 9}
- 1 → 1
- 1 → 6
- 3 → 7
- 6 → 9
✘ 1 maps to both 1 and 6 → violates function rule.
➡️
Function: NO
---
4)
Domain: {1, 2, 5, 7, 8}
Range: {1, 2, 3, 4}
- 1 → 1
- 2 → 3
- 5 → 4
- 7 → 3
- 8 → 4
✔ Each input maps to
only one output.
Multiple inputs (like 2 and 7) go to 3 — allowed.
➡️
Function: YES
---
5)
Domain: {0, 2, 5, 6, 7}
Range: {0, 2, 6, 8}
- 0 → 0
- 0 → 2
- 0 → 6
- 0 → 8
- 2 → 2
- 5 → 6
- 6 → 8
- 7 → 0
✘ 0 maps to four different values → not allowed.
➡️
Function: NO
---
6)
Domain: {3, 4, 7}
Range: {3, 5, 8}
- 3 → 3
- 4 → 3
- 7 → 3
✔ All inputs map to
only one output (even though all go to 3).
➡️
Function: YES
---
7)
Domain: {4, 5, 8, 9}
Range: {0, 4, 7, 8, 9}
- 4 → 0
- 4 → 4
- 4 → 7
- 5 → 8
- 5 → 9
- 8 → 0
- 9 → 4
✘ 4 maps to 0, 4, and 7 → multiple outputs
✘ 5 maps to 8 and 9 → multiple outputs
➡️
Function: NO
---
8)
Domain: {0, 1, 8, 9}
Range: {1, 2, 7}
- 0 → 1
- 1 → 2
- 8 → 7
- 9 → 1
✔ Each input has exactly one output.
Even though 0 and 9 both map to 1 — that's okay.
➡️
Function: YES
---
✔ Final Answers:
| Diagram | Function? |
|--------|-----------|
| 1) | Yes |
| 2) | No |
| 3) | No |
| 4) | Yes |
| 5) | No |
| 6) | Yes |
| 7) | No |
| 8) | Yes |
---
📝 Summary:
To determine if a mapping diagram is a function:
- Check if
any input (left side) connects to
more than one output (right side).
- If
yes →
Not a function.
- If
no →
It is a function.
✔ Only
diagrams 1, 4, 6, and 8 are functions.
✘ Diagrams 2, 3, 5, and 7 are
not functions due to multiple outputs from a single input.
Let me know if you'd like this printed out or formatted as a worksheet!
Parent Tip: Review the logic above to help your child master the concept of domain and range worksheet pdf.