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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

    VietDao29

    User Avatar
    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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