Which of the following relations is a function?

A. { (-2, 4), (-1, 3), (5, 2), (1, 4) }
B. { (1, 7), (1, 8), (2, 7), (3, 8) }
C. { (2, 4), (4, 6), (4, 8), (6, 4) }
D. { (5, 7), (6, 3), (8, 6), (5, 4) }

Question

Which of the following relations is a function?

A. { (-2, 4),  (-1, 3),  (5, 2),  (1, 4) }
B. { (1, 7),  (1, 8),  (2, 7),  (3, 8) }
C. { (2, 4),  (4, 6),  (4, 8),  (6, 4) }
D. { (5, 7),  (6, 3),  (8, 6),  (5, 4) }

anonymous · Answer

D . 
 Look at the first numbers if they duplicate it is not a function

hoblos · Answer

in a function there is a unique value of y for each value of x

so  only the  first one can be a function

hoblos · Answer

it is A

anonymous · Answer

thats what i was about to ask bc D has 5

anonymous · Answer

that duplicates

anonymous · Answer

i must be blind :) then it would be A (:

anonymous · Answer

(: it was a simple mistake but your comment helped me out alot! Thanks guys!