Question

Which of the following relations represent a function?

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

Answer 1

{(-1,4), (2,7), (3,7)} is a function

Step-by-step explanation:

For something to be a function, any given x must have one and only one y

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

-1(x) only has -3(y)

3(x) has 2(y) and 7(y), making it not a function

{(-3,7), (3,-7), (3,7)}

-3(x) only has 7(y)

3(x) has -7(y) and -7(y, making it not a function

{(-1,4), (-1,7), (3,5)}

3(x) only has 5(y)

-1(x) has 4(y) and 7(y), making it not a function

{(-1,4), (2,7), (3,7)}

-1(x) only has 4(y)

2(x) only has 7(y)

3(x) only has 7(y)

This is a function

Answer 2

You must find the set that doesn't have a repeating x value.

looking at the first set you can see that there are two 3's
looking at the second set you can see that there are also tow 3's
looking at the third set you can see that there are two -1's
looking at the fourth set you can see there is nothing that is repeating in the x values. So the fourth set would be your answer.