#1: To be a function - What can NOT repeat? Select ALL that apply. Domain
Range
x-coordinate
y-coordinate
Input
Output

To be a function, the DOMAIN, the X-COORDINATE, and the INPUT VALUES cannot repeat.

For example, the coordinates (3,6) and (5,6) are good, but if you were to have the coordinates (3,7) and (3,9), that would not be a function.