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Sequences and Series

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Question 39

Consider the finite geometric series defined by the summation ∑i=0n−1ARi\sum_{i=0}^{n-1} A R^i∑i=0n−1​ARi.

Prove that the sum Sn S_n\,Sn​ of this series is given by the formula

Sn=A(1−Rn)1−R S_n = \frac{A(1 - R^n)}{1 - R} Sn​=1−RA(1−Rn)​
[4]

Sequences and Series Questions

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