There is only one main thing you need to check in order to see if a mapping between two sets of numbers is a function. You check to make sure each input has a unique output. If your map has two different possible outputs for a given input then it is not a function. It's that simple!

The relation you described is below:

`{(2,3),(-2,3),(3,3),(-3,5)}`

Now, we just look at our inputs:

2, -2, 3, -3

We look to see whether there are **two of the same input** giving a different output, which we don't!

Therefore, the relation is a function.

Don't get mixed up, though, with this relation! notice that (-2,3) and (3,3) both map their inputs to the same output! However, this is allowed for functions. The main thing for functions is **only one possible output for an input**, but it doesn't matter if you have many inputs leading to the same output.

I hope that helps you out!