Which relations are functions and which are not functions?

Column A Column B

1.

{ (3, 2), (6, 4), (9, 6),

(12, 8) }

2.

{ (2, 3), (2, 5), (3, 6),

(9, 4) }

3.

{ (4, 2), (6, 3), (4, 8),

(6, 6) }

4.

{ (3, 4), (5, 2), (6, 8),

(6, 4) }

A.

function

B.

not a function

If the x value is repeated is is not a function. (unless it is a negative and a positive)

So lets see:

For A we have 3 6 9 12 no repeations so therefore It is A

For B we have 2 2 3 9, 2 is repeated so therefore it is B

For C we have 4 6 4 6, both 4 and 6 were repeated so therefore is is B

and lastly for D we have 3 5 6 6

And 6 was repeated so therefore it is B.

A) A

B) B

C) B

D) B