Which of the following is a function?

a. { (-4,1), (1,8), (-4,-2) }

b. { (-4,1), (1,-8), (-2,-2) }

c. { (-4,1), (1,-8), (1,-2) }

d. none of these

The expression b. { (-4,1), (1,8), (-4,-2) } is a function

b.

Step-by-step explanation:

The expression b is a function because the x values are all different.

In fact it is a one-to-one function as there is a different value of y for each value of x.