How do you know if (4,5) (3, -2) (-2,5) (4,7) is a function?

Aug 14, 2016

As soon as there is a choice for y, it is NOT a function.

Explanation:

It is NOT a function.

Notice that when $x = 4$, there are two possible answers for $y$

In a function, for each x-value there must be only ONE y-value.

As soon as there is a choice for y, it is NOT a function.