Question

Which set of ordered pairs does not represent a function?

{(8,-2), (6,-1), (4,1), (0,1)}
{(8,4), (1,5), (-7,7), (9,5)}
{(4,-6), (-3,2), (7,-1), (-6, -4)}
{(-9,3), (8,7), (-9, -9), (2, 4)}

Answer 1

Answer: Choice D

{(-9,3), (8,7), (-9, -9), (2, 4)}

=======================================================

Step-by-step explanation:

To find an example of a non-function, we look for (x,y) points where x repeats itself. That occurs in choice D where we have (-9,3) and (-9,-9) in the same function set.

The input x = -9 leads to multiple outputs y = 3 and y = -9 simultaneously. This is not allowed if we wanted a function.

A function is only possible if each input x leads to exactly one y output.

So this is why we look for repeated x values when trying to find non-functions. Choices A, B and C all have unique x values that don't repeat, which means those choices represent functions.

Side note: The y values can repeat, but the function won't be one-to-one.