Question

Which of the following is not a function?
Click on the graph until the correct graph appears.

Answer 1

are there any more? that first IS a function...

Answer 2

That's a function.

Answer 3

Stop.

Answer 4

That's not a function.

Answer 5

The reason that is not a function is because for every y-value you have, you can only have one x-value. (3, 1) and (3, 2) would prove that whatever that is -it's not a function. If you look at your graph and on any give x-line (vertical line) there is more than one point, then it is not a function. This is called the vertical-line test.