Question

Determine which relation is a function.


A.


{(–5, 1), (–5, 0), (–2, 1), (–1, 4), (6, 2)}


B.


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


C.


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


D.


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

Answer 1

A relation is only a function if and only if each x pairs with EXACTLY ONE y value


If we had something like this relation

{(1,2), (3,4), (1,7), (10,9)}

This relation is NOT a function because x = 1 pairs up with y = 2 and y = 7. The input is x = 1, but what is the output? is it y = 2? or is it y = 7? This ambiguity means that we don't have a function.

Answer 2

Look at the points given in relation A. Do any of them have the same x value? If so, what does that tell you about the relation? In other words, is the relation a function or not a function?