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Homework Help: Summation Formula help

  1. Jul 22, 2010 #1
    I am trying to Sum the total from the following equation B(t)=a * b^t

    So I have [tex]\sum[/tex] a * b^t with t=1 to 321

    Trying to solve for an equation and getting a(b^(t+1) - 1) / (b-1)

    Answer is not correct...help
  2. jcsd
  3. Jul 22, 2010 #2


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    Science Advisor

    The answer you are presenting is for t starting at 0 not 1. The correct result would be:
    ab(b321 - 1)/(b - 1).
    Last edited: Jul 22, 2010
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