Which of the sets of ordered pairs represents a function?

A = {(−4, 5), (1, −1), (2, −2), (2, 3)}

B = {(2, 2), (3, −2), (9, 3), (9, −3)}

Question

Which of the sets of ordered pairs represents a function? 

A = {(−4, 5), (1, −1), (2, −2), (2, 3)} 

B = {(2, 2), (3, −2), (9, 3), (9, −3)}

anonymous · Answer

I have no clue where to start with this one...

anonymous · Answer

A function: an input, x, has only one output, y.

I think you can work with that.

anonymous · Answer

umm, im not sure what you mean

anonymous · Answer

So if A, just an example, said (1, 1), (1, 7), (2, 9), (2, 4), it would not be a function.

anonymous · Answer

An example of a function is:
(1, 2)
(2, 3)
(3, 4)
(4, 5)

anonymous · Answer

Each input, the first number, can only have one output.

anonymous · Answer

Sooo, neither of them are a function?

anonymous · Answer

One of them is indeed a function.

anonymous · Answer

Im pretty sure its the top one???

anonymous · Answer

So look at A.

It has (2, -2) and (2, 3)

So A cannot be a function.

anonymous · Answer

ohhh I think I get it now

anonymous · Answer

Only an input, a number like 5, can have only one output, like 7.

anonymous · Answer

Ok thank you for your help.

anonymous · Answer

Leave a medal if I helped btw.

anonymous · Answer

and how do I leave a medal?

anonymous · Answer

You click on the blue button entitled "Best Response."

anonymous · Answer

There you go

anonymous · Answer

Thanks again

anonymous · Answer

Thank you, if you need anymore help PM Me.