Is {(1, 2), (2, 4), (3, 6)} a function

Step by step

The question

Question: is {(1, 2), (2, 4), (3, 6)} a function?

A function is a rule where each x has only one y.

One x in, one y out.

1 Each x and its y

We take each x and see where it goes.

1 goes to 2.

2 goes to 4.

3 goes to 6.

2 Read the answer

Every x has only one y.

So yes, it is a function.

3 Check

Let's check on a grid.

Draw the grid.

We plot the points.

A straight up-and-down line meets at most one point.

Here at x = 1: one point.

No up-and-down line meets two points.

It is a function.

The same answer!

Let's look back.

First: each x and its y.

Then: read the answer.

Last: check.