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Math Help - Help with series...

  1. #1
    Junior Member
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    Exclamation Help with series...

    From the series:16, 14, 12, 10......

    (a) Find Tn
    (b) Find Sn
    (c) Find the sum of the first 12 terms.

    I am not sure how to do this as I was not given any information in class. Also if you know any articles on this, could you please post a link.

    THANKS
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  2. #2
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    Quote Originally Posted by holmesb View Post
    From the series:16, 14, 12, 10......

    (a) Find Tn
    (b) Find Sn
    (c) Find the sum of the first 12 terms.

    I am not sure how to do this as I was not given any information in class. Also if you know any articles on this, could you please post a link.

    THANKS
    This seems like an arithmetic sequence:
    t_n = 18 - 2n

    The sum of term is,
    18 - 2(1) + 18 - 2(2) + ... + 18 - 2(n)
    Rewrite,
    \underbrace{(18+18+...+18)}_n - 2(1+2+...+n)
    Add,
    18 n - 2\cdot \frac{n(n+1)}{2} \Rightarrow 18 n - n^2 - n  = 17n - n^2
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  3. #3
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    Lexington, MA (USA)
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    Hello, holmesb!

    From the series: 16, 14, 12, 10, ...

    (a) Find T_n
    (b) Find S_n
    (c) Find the sum of the first 12 terms.

    I am not sure how to do this as I was not given any information in class.

    You were given no information ???
    . . Then you don't know that T_n means . . . or S_n

    Better wait until your teacher explains all this . . .

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