Question

Which of the sets of ordered pairs represents a function?

Answer 1

- - A function must not repeat of the same x value.

For example: (-4,4) (5,3) (5,6) is not a function because the 5 value repeats more than once. 

For A, the x values are: 2,5,-2,-5
Nothing repeats more than once. (Please keep in mind that if its a negative, it will not be the same as a positive because they lie on 2 different sides of the coordinate grid.) 

Now for B: 4,4,9,9 
The 9 is repeated, leaving it not a function.

If you have anymore questions upon functions feel free to ask me, as I am very very good at them! :P 

Your final answer would be A, because it does not repeat in the x value. <span />

Answer 2

Only A is a function because it is the only one with just one input for every output. Function B has 4 in the x position twice.