Answer:
Yes
No
Yes
No
Explanation:
If you see the same number used more than once as an x-coordinate, then it is not a function. If all x-coordinates are different, then it is a function.
(2, 2), (3, 3), (4, 4), and (5, 5) Yes. All x-coordinates are different.
(1, 2), (1, 3), (1, 4), and (1, 5) No. The same number is used more than once as an x-coordinate.
(2, 1), (3, 1), (4, 1), and (5, 1) Yes. All x-coordinates are different.
(2, 2), (2, 3), (5, 4), and (5, 5) No. 2 is used more than once for x, and the same happens with 5.