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Geometric series. Find the sum of the series. Powers.

  1. Sep 13, 2010 #1
    1. The problem statement, all variables and given/known data

    Find the sum of 9 terms of the series 3 + 3^(4/3) + 3^(5/3) + ...

    2. Relevant equations

    I'm just learning sequences and series and senior high school level. I'm finding it hard to apply a, ar, ar^(n-1), ... to this.

    a = 3.

    I don't know how to find common ratio. I'm confused. Once I know r I can apply the standard formula for summing the series.

    3. The attempt at a solution
    1. The problem statement, all variables and given/known data

    2. Relevant equations

    3. The attempt at a solution

    Any help will be greatly appreciated.
  2. jcsd
  3. Sep 13, 2010 #2


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    Homework Helper

    In geometric series, the following term is obtained by multiplying the previous term by the common ratio r. Which, in turn, means that, you can obtain r by dividing the following term by the previous term; like this:

    [tex]r = \frac{a_2}{a_1} = \frac{a_3}{a_2} = ... = \frac{a_n}{a_{n - 1}}[/tex]

    So, can you calculate the common ratio in the problem above?
  4. Sep 13, 2010 #3
    Yes! I got it now. Thanks for your help!
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