Which of these relations is a function?

[clljhns]

Help! I don't understand this question.

Which of these relations is a function?

1. {0,1} {1,2} {2,4}
2. {0,1} {0,2} {0,3}
3. {0,1} {1,2} {1,4}
4. {0,1} {0,2} {2,4}

[nona.m.nona]

Help! I don't understand this question.

To learn how to recognize a function from a list of points, please review the following lesson:

Functions: Domain and Range

[clljhns]

Thanks! I understand!