Question 484494
A function requires that every input have only one output. In other words, if we have pairs that represent (input, output), if there exists a certain value for input in some pair, it should not occur again, unless of course it describes the same output.

The input value 2 causes a problem. It has outputs 3, 5, and 7. Since there is more than one output for some input, in this case 2, this relation does NOT satisfy the requirement to be a function as well.