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Thread: Geometric progression

  1. #1
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    Geometric progression

    P = a1 + a4 + a7 + a10..... + a34
    Q = a2 + a5 + a8 + a11 .... + a35

    how many terms in each one?

    The answer is 12


    * i came to conclusion that the q for each one is q3
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  2. #2
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    Re: Geometric progression

    It is certainly true that both 1, 4, 7, ..., 34, and 2, 5, 8, ..., 35 are arithmetic sequences with common difference 3 so, since 34= 1+ 3(11), and 35= 2+ 3(11), each has 11+ 1= 12 terms. I have no idea what "the q for each one is q^3" means.
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    Re: Geometric progression

    Quote Originally Posted by HallsofIvy View Post
    It is certainly true that both 1, 4, 7, ..., 34, and 2, 5, 8, ..., 35 are arithmetic sequences with common difference 3 so, since 34= 1+ 3(11), and 35= 2+ 3(11), each has 11+ 1= 12 terms. I have no idea what "the q for each one is q^3" means.
    What's the 11 for?
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  4. #4
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    Re: Geometric progression

    Quote Originally Posted by Mustafashama View Post
    What's the 11 for?
    $P=\{a\times a^n:n=0,1,2,3,4,5,5,6,7,8,9,10,11\}$
    That is twelve values of $n$.
    Last edited by Plato; Jun 17th 2017 at 07:09 AM.
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