Ok, a function means that the domain (x) does not repeat... so if you look at all of the first numbers in the ordered pairs or x and none of them are repeating in the set that is your answer. For this the answer would be 1 and not 2 because x has a exponent making it 2 x and not 3 because there is 2 10s. Let me know if this helps and you have any other questions.
