Question

Which relation is not a function?
1. {(1,5), (2,6), (3,6), (4,7)}
2. {(4,7), (2,1), (-3,6), (3,4)}
3. {(-1,6), (1,3), (2,5), (1,7)}
4. {(-1,2), (0,5), (5,0), 2,-1)}

Answer 1

A function must have a unique y-value for every x-value. There cannot be two x-values with different y-values.

Answer 2

Let me know what you think is not a function.

Answer 3

2?

Answer 4

Try taking a look at number 3 and number 2. One of them has a repeating x- value, but that value is given two different y-values.
Hint: {1, ?}

Answer 5

Do you see what I am talking about?
If for example we have {5,3} {5,7} {1,2} {3, 4}
This would not be a function, as there are two different y-values for the x-value of 5. Therefore it would fail the vertical line test.

Answer 6

So try looking one more time at which one would not pass the vertical line test.

Answer 7

oh so it would be 3 because the 1s have two different y values

Answer 8

Correct.
Great job!

Answer 9

Thank you!

Answer 10

You're welcome. :)