Question

Which of the following sets represents a function?

{(3, 5), (-1, 7), (3, 9)}
{(1, 2), (3, 2), (5, 7)}
{(1, 2), (1, 4), (1, 6)}

Answer 1

Choice A is not a function because x = 3 repeats itself. We have x = 3 leading to more than one y value.

The same applies for choice C. The x value x = 1 repeats itself.

The only case where this doesn't happen is with choice B. The unique x values indicate we have a function. For any given x, there is EXACTLY ONE output.

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Answer: Choice B

Answer 2

Answer with Step-by-step explanation:

A function is a relation in which each input has only one output.

i.e. if a relation contains an ordered pair (x,y) then x is the input and y is the output

{(3, 5), (-1, 7), (3, 9)}

It is not a function

Since, input 3 has two output values 5 and 9

{(1, 2), (3, 2), (5, 7)}

It is a function

Since each input has only one output

{(1, 2), (1, 4), (1, 6)}

It is not a function

Since, input 1 has three output values 2,4 and 6