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Math Help - Geometric and Arthmetic terms

  1. #1
    Newbie amandaggogo's Avatar
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    Geometric and Arthmetic terms

    Please help me out, Its drivin gme crazy because I cant answer it.


    Find the sum of the first 29 terms 4,8,16,32
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  2. #2
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by amandaggogo View Post
    Please help me out, Its drivin gme crazy because I cant answer it.


    Find the sum of the first 29 terms 4,8,16,32
    As U_{n+1} = 2U_n then you have a geometric sequence with \text{a = 4, n = 29, r = 2}

    The formula for the sum of a geometric sequence is

    S_n = \frac{a(r^n-1)}{r-1}. Sub in your values and solve

    Spoiler:
    S_{29} = \frac{2(2^{29}-1)}{2-1} = 1 073 741 822
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  3. #3
    Newbie amandaggogo's Avatar
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    Thank you very much, that makes much more sense now :0)
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