Which sets of ordered pairs represent relations that are functions? you may choose more than one correct answer.
{(1, 0), (2, 0), (3, 0), (4, 0)}
{(2, 3), (2, 4), (2, 5), (2, 6)}
{(1, 1), (2, 2), (3, 3), (4, 4)}
{(1, 3), (-1, 4), (1, 4), (-1, 3)}
{(6, -6), (-6, 6), (5, -5), (-5, 5)}

Step-by-step explanation:

A relation from a set X to a set Y is called a function, if each element of X is related to one and exactly one element in Y. Though many elements of X can be related to one element in Y (many to one).

As in the second option all the values of Y are related to one X i.e 2, so this is not a function.

In 4th option there are two points (1, 3), (1, 4) and (-1, 4), (-1, 3), they share same value from X, so this is not a function.

Option 1, 3, 5 are correct.