Question

Select all the relations that represent a function.

1. (1, 3), (2, 5), (2, 7) (4,9)
2. (1, 3), (2, 5), (3, 7) (4,9)
3. (1, 3), (1,5), (1, 7) (4, 9)
4. (1,3), (2, 3), (3, 3) (4, 3)
5. (1, 2), (2, 5), (2, 1) (4, 5)

Answer 1

1. (1, 3), (2, 5), (2, 7) (4,9) No

2. (1, 3), (2, 5), (3, 7) (4,9) Function

3. (1, 3), (1,5), (1, 7) (4, 9) No

4. (1,3), (2, 3), (3, 3) (4, 3) Function

5. (1, 2), (2, 5), (2, 1) (4, 5) No

Explanation:

If you see the same x-coordinate more than once in a relation, then that relation is not a function.

1. (1, 3), (2, 5), (2, 7) (4,9) The 2 is used more than once as a x-coordinate. Not a function.

2. (1, 3), (2, 5), (3, 7) (4,9) All x-coordinates are different. Function.

3. (1, 3), (1,5), (1, 7) (4, 9) The 1 is used more than once as an x-coordinate. Not a function.

4. (1,3), (2, 3), (3, 3) (4, 3) All x-coordinates are different. Function.

5. (1, 2), (2, 5), (2, 1) (4, 5) The 2 is used more than once as a x-coordinate. Not a function.