Question

In which set of ordered pairs, (x, y), is y not a function of x?

Answer 1

For y to not be a function of x, there needs to be an x-value that is paired with more than one y-value.

In terms of the sets, you need to find a set where the same x-value is used more than once in two (or more) different (x,y) pairs.

This occurs in the third set, where x=6 is used twice.