Question

Which relation is not a function?

{(1,5), (2,6), (3,6), (4,7)}
{(4,7, (2,1), (-3,6), (3,4)}
{(-1,6), (1,3), (2,5), (1,7)}
{(-1,2), (0,5), (5,0), (2,-1)}

Answer 1

Answer: C

Explanation:

The X value repeats itself

Answer 2

Explanation: In order for a function not to be a relation,

each x-coordinate must correspond to more than one y-coordinate.

Notice that in third relation, the 1 pairs with a 3

in one case and it pairs with a 7 in the other case.

Since each x-coordinate pairs with more than one y-coordinate,

this relation is not a function but the other ones are functions.