Q9. (a) All the terms of a geometric progression are positive.
The second and fourth terms are shown.
4.
16
Work out the first and third terms.
First term
Third term

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