Question

On a coordinate plane, solid circles appear at the following points: (negative 3, negative 3), (negative 3, 2), (1, 1), (2, negative 2), (3, 4), (4, negative 2).
Which ordered pair could be removed so that the set of ordered pairs is a function?

(4, –2)
(–3, 2)
(3, 4)
(1, 1)

Answer 1

Remove (−3, 2).

A relation is a function if each x-value appears at most once. Here x = −3 appears twice (at (−3, −3) and (−3, 2)); removing (−3, 2) leaves only one point with x = −3, so the remaining set is a function.