Which of the following relations is a function?
{ (1, 2), (1, 3), (2, 8), (3, 9) }
{ (1, 2), (2, 3), (3, 4), (4, 5) }
{ (3, -1), (2, 3), (3, 4), (1, 7) }
{ (3, 0), (4, -3), (6, 7), (4, 4) }

Question

Which of the following relations is a function?
{ (1, 2),  (1, 3),  (2, 8),  (3, 9) }
{ (1, 2),  (2, 3),  (3, 4),  (4, 5) }
{ (3, -1),  (2, 3),  (3, 4),  (1, 7) }
{ (3, 0),  (4, -3),  (6, 7),  (4, 4) }

mathmale · Answer

Hint #1:  In any point, such as (1,2), the first number represents the x-value and the second number represents the y-value.

Hint #2:  You can recognize a function by noting that the same x-value never shows up more than once.  In other words, for any particular x-value contained in the set of points, there is exactly one y-value, NO more.

anonymous · Answer

b

mathmale · Answer

Mind explaining your reasoning, please?  Don't feel picked on; I almost always ask that.

anonymous · Answer

because you said the x value is never the same

mathmale · Answer

Right.  In (b), there are four distinct x-values; no single x-value shows up more than once.  Right.  Nice work.

anonymous · Answer

thanks

mathmale · Answer

My great pleasure!

anonymous · Answer

think you can help me with another one ?

mathmale · Answer

sure...go ahead and post it (but separately from this problem, please).

anonymous · Answer

nevermind I got it, I appreciate it though

mathmale · Answer

Sure.