Question

Which of the following lists of ordered pairs is a function?

A. (4, 2), (4, -2), (9, 3), (16, 4)
B. (9, 4), (5, 0), (1, -4), (-2, -6)
C. (1, 2), (0, 3), (1, 4), (6, 5)
D. (9, 4), (5, 0), (5, 3), (-2, -6)

Answer 1

A function is a set of ordered pairs in which no two ordered pairs have the same first number.

Answer 2

the set that has no X-Repeats
let's take a look at the 1st one, does it have a x-coordinate repeat?
\(\bf A.\qquad ({\color{red}{ 4}}, 2), ({\color{red}{ 4}}, -2), (9, 3), (16, 4)\)

low and behold, it does, thus is NOT a function
check the others