which of the following expressions represents a function?
x² + y² = 9
{(4,2), (4, -2), (9,3), (9, -3)}
x=4
2x + y = 5

Suppose you are choosing a 6-digit personal access code. this code is made up of 4 digits chosen from 1 to 9, followed by 2 letters chosen from a to z. any of these digits or letters can be repeated. find the total number of personal access codes that can be formed. 492,804 341,172 39,917,124 4,435,236