Which of the following relations is a function?
{ (1, 2), (1, 3), (1, 4), (1, 5) }
{ (1, 3), (2, 3), (4, 3), (9, 3) }
{ (5, 4), (-6, 5), (4, 5), (4, 0) }
{ (6, -1), (1, 4), (2, 3), (6, 1) }

A function will NOT have any repeating x values, it can have repeating y values, just not the x ones. So which set has NO repeating x values ?
That would be { (1,3), (2,3), (4,3), (9,3)}like I said, there can be repeating y valuesjust not the x ones. All of ur other answer choices have repeating x values.