Question

Which relation is a function?

Answer 1

The relation that is a function is that represented in the fourth graph. y = 2IxI

You must know that for a relation to be a function, there can not be two different values of f (x) for the same value of x.

In other words, if we have two sets P and M.

A function "f" between them is a relation that assigns to each value of the set P a single value of the set M.

To quickly verify when observing a graph it draws vertical lines and if they cut the graph in two points then the relation is not a function because it assigns two different values of f (x) for the same value of x.

By doing this test you will verify that only the fourth image represents the graph of a function.