Question

PLZ HELP I DON'T UNDERSTAND :(

Which of the following relations is a function?
A.
(9, 1), (-1, 4), (4, 1), (9, 2)

B.
(4, 0), (-1, 3), (9, 1), (-1, 5)

C.
(4, 4), (-1, 2), (9, 1), (-7, 2)

D.
(4, 4), (-1, 6), (4, 3), (-7, 2)

Answer 1

A

Explanation:

If there are two points that are the same y value then it is not a function. So in answer a (9,1) and (4,1) have the same y value and so would not pass the vertical line test and is not a function.