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    IBMediumSequences10–12

    Geometric Series Sum

    Soma de Série Geométrica

    Find the sum of the first 8 terms of the geometric series: 3 + 6 + 12 + 24 + \ldots

    Use S_n = \frac{a(r^{n} - 1)}{r - 1}. Identify the first term a and the common ratio r from the series itself.

    Solution

    Step 1 of 4

    1. 1.a = 3, r = \frac{6}{3} = 2, n = 8