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Homework Help: Evaluate summation

  1. Apr 25, 2010 #1
    1. The problem statement, all variables and given/known data

    evaluate
    [tex]\sum[/tex][tex]\frac{1}{e^n}[/tex] from 0 -> infinity

    2. Relevant equations

    N/A

    3. The attempt at a solution

    from what i've learn, i can calculate summation i in form

    [tex]\sum[/tex]na ,a is integer
    or
    [tex]\sum[/tex] f(n+1)-f(n)

    but how to make 1/e^n in any those form?
    can give me any clue please
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Apr 25, 2010 #2

    LCKurtz

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    Hint: Think about geometric series
     
  4. Apr 25, 2010 #3
    [tex]\sum[/tex]([tex]\frac{1}{e}[/tex])n

    yes, why am i so stupid didn't think of that =.=

    thank you very much
     
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