A true function can only have one specific y-value for each x-value.
Therefore, something like this would NOT be a function:
(2,3), (2,0) there are two y-values for the same x-value (not a function)
However, this example WOULD be a function:
(2,3), (4,4), (5,2), (3,2)
it is still a function even if there are two of the same y-values for two different x-values. There just can't be two same x-values with different y-values.
Hope that helps!
