Question

Which sets of ordered pairs represent functions from A = {1, 2, 3, 4} to B = {−1, 0, 1, 2, 3}? Justify.

{(1, 2), (2, −1), (3, 1), (4, 3)}

Answer 1

Let f = {(1, 2), (2, −1), (3, 1), (4, 3)}

f is a function because every element of A is related to one and only one element of B.