Step by step
The question
Question: is {(2, 2), (3, 3), (2, 4)} a function?
{(2, 2), (3, 3), (2, 4)}
A function is a rule where each x has only one y.
One x in, one y out.
function: each x has only one y
1 Each x and its y
2 goes to 2 and 4.
One x, two different y's!
2 → 2, 4
3 goes to 3.
3 → 3
2 Read the answer
2 has two y's.
So it is not a function.
= no, not a function
3 Check
Let's check on a grid.
Draw the grid.
We plot the points.
A straight up-and-down line at x = 2 meets two points.
Two points on one up-and-down line: not a function.
The same answer!
Let's look back.
First: each x and its y.
Then: read the answer.
Last: check.
Answer
= no, not a function