# What is the sum of the first 9 terms of the given geometric sequence?

ALgebra problem

### 2 Answers

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- KrishnamurthyLv 74 weeks ago
3, 9, 27, 81, ...

an = 3^n

a9 = 19683

sum_(n=1)^9 3^n = 29523

Answer option:

A. 29,523

- Wayne DeguManLv 74 weeks ago
3, 9, 27, 81,...1st term 3 and common ratio 3

Sₙ = a(rⁿ - 1)/(r - 1)

so, Sₙ = 3(3ⁿ - 1)/2

Then, S₉ = 3(3⁹ - 1)/2 => 29,523

Note: 3 + 9 + 27 + 81 + 243 + 729 + 2187 + 6561 + 19683 = 29523

:)>

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