Which of the following lists of ordered pairs is a function?
a. (1, 2), (0, 3), (1, 4), (6, 5) b. (9, 4), (5, 0), (1, -4), (-2, -6)
c. (4, 2), (4, -2), (9, 3), (16, 4) d. (9, 4), (5, 0), (5, 3), (-2, -6)

A. (1, 2), (0, 3), (1, 4), (6, 5)
It's not a function, becouse:
(1, 2): 1 ⇒ 2 and (1, 4) - 1 ⇒ 4

B. (9, 4), (5, 0), (1, -4), (-2, -6)
It's a function

C. (4, 2), (4, -2), (9, 3), (16, 4)
It's not a function, becouse:
(4, 2): 4 ⇒ 2 and (4, -2): 4 ⇒ -2

D. (9, 4), (5, 0), (5, 3), (-2, -6)
It's not a function, becouse:
(5, 0): 5 ⇒ 0 and (5, 3): 5 ⇒ 3

So a function is basically the x values don't repeat with any differnt y values
(x,y)

the first number should never repeat with a differnt y value

A. 1 repeats with2 and 4, not a function
B.. no repeat, it's a function
C. 4 repeats with 2 and -2,not a function
D. 5 repeats with 0 and 3, not a function

answer is B