Let a,b,c are respectively the sums of the first n terms, the next n terms and the next n terms of a GP. Show that a,b,c are in GP.

Explanation

To show that \( A, B, C \) are in geometric progression (GP), we need to prove that \( B^2 = AC \). Let's break down the solution step by step.

### Step 1: Finding \( A \)

The sum of the first \( n \) terms of a geometric progression (GP) is given by the formula:

\[
A = S_n = \frac{A_1 (r^n - 1)}{r - 1}
...