Find the sum to indicated number of terms in each of the geometric progressions : `1,-a ,a^2-a^3,dotdotdotn`terms `(if a!=- 1)`

Explanation

To find the sum of the first n terms of the geometric progression (GP) given by the series \(1, -a, a^2, -a^3, \ldots\), we can follow these steps:

### Step 1: Identify the first term and the common ratio
The first term \(A\) of the GP is:
\[ A = 1 \]

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