Question

Which of the following relationships represents a function?

Answer 1

D

Explanation:

You can not have multiple outputs for an input in a function.

In A, input x = -1 has multiple y values

In B, x = -5 has multiple y values

In C, x = 5 has multiple y values

Only D has a unique y value for every x

Answer 2

The answer would be D.

To be a function for each unique x value you need one y value.

In A there are two -1 x values but each one has a different y value. To be a function they would need to have the same y value... this is the same for b and c as well.