To determine if a mapping diagram represents a function, we need to check one simple rule:
Every number in the left oval (the input) must point to exactly one number in the right oval (the output).
- If a number on the left has
more than one arrow coming out of it, it is
NOT a function.
- If every number on the left has exactly one arrow, it
IS a function.
Let's go through each problem step-by-step:
1.
Diagram 1:
- Look at the number
2. It has two arrows coming out of it (pointing to 0 and 9).
- Because one input has two outputs, this is
Not a Function.
2.
Diagram 2:
- Look at the number
9. It has two arrows coming out of it (pointing to 3 and 8).
- Because one input has two outputs, this is
Not a Function.
3.
Diagram 3:
- Number
1 points to 9.
- Number
3 points to 9.
- Number
6 points to 9.
- Every input has exactly one arrow. Even though they all point to the same thing, that is allowed.
- This
Is a Function.
4.
Diagram 4:
- Look at the number
1. It has two arrows coming out of it (pointing to 3 and 4).
- Because one input has two outputs, this is
Not a Function.
5.
Diagram 5:
- Look at the number
0. It has two arrows coming out of it (pointing to 0 and 6).
- Because one input has two outputs, this is
Not a Function.
6.
Diagram 6:
- Number
3 points to 3.
- Number
4 points to 3.
- Number
7 points to 3.
- Every input has exactly one arrow.
- This
Is a Function.
7.
Diagram 7:
- Look at the number
4. It has two arrows coming out of it (pointing to 4 and 9).
- Because one input has two outputs, this is
Not a Function.
8.
Diagram 8:
- Number
0 points to 1.
- Number
1 points to 2.
- Number
8 points to 7.
- Number
9 points to 7.
- Every input has exactly one arrow.
- This
Is a Function.
Final Answer:
1) Not a Function
2) Not a Function
3) Function
4) Not a Function
5) Not a Function
6) Function
7) Not a Function
8) Function
Parent Tip: Review the logic above to help your child master the concept of finding domain and range from a graph worksheet.
