Which of the following is not a function?
A 2-column table with 4 rows. Column 1 is labeled x with entries 1, 2, 2, 3. Column 2 is labeled y with entries 3, 4, 5, 9.
A 2-column table with 4 rows. Column 1 is labeled x with entries negative 2, 1, 2, 3. Column 2 is labeled y with entries 0, 3, 4, 7.
y = 3x² – 6x + 4
{(3, 4), (6, 5),
(7, 9), (9, 15)}