To be a function, a relation can't have more than 1 value of 'y' for the same value of 'x'
For example, if you have points (3,7) and (3,-6) does not represent a function but points (3,7) and (-3,7) does.
In this problem, none of the graphed pairs have 2 or more values of 'y' for a single value of 'x'. They are all different, so yes, this relation is a function
