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Find a closed form for the nth partial sum, and determine whether the series converge

  1. Mar 25, 2012 #1
    1. The problem statement, all variables and given/known data

    Find a closed form for the nth partial sum, and determine whether the series converges by calculating the limit of the nth partial sum.

    1. 2+2/5 + 2/25+.....2/5k-1

    2. Relevant equations



    3. The attempt at a solution

    What I did was I found out it was a geometric sequence.

    with R = .2

    sn=2+2/5+2/25+2/5n-1

    .2sn= 2/5+2/25+2/125+2/5n


    I subtract the equations giving me

    .8sn=2+2/5n

    I divide .8 to both sides giving me

    sn= 5/2+1/2n

    I know I am messing up with the multiplication / subtraction of the Nth term much help is appreciated (:
     
  2. jcsd
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