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Math Help - Find the arithmetic sequence

  1. #1
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    Find the arithmetic sequence

    Determine an arithmetic sequence knowing the sum Sn if its n first terms is equal to 6n^2 + 7n. For any non zero n
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  2. #2
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    Re: Find the arithmetic sequence

    Start from here: \frac{n}{2}(2a+(n-1)d)=6n^2+7n
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  3. #3
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    Re: Find the arithmetic sequence

    When n=1 we get the first term. That is 13. When n=2 we get sum of 1st 2 terms = 38 Hence 2nd term= 25 So common difference = 12
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    Re: Find the arithmetic sequence

    Quote Originally Posted by biffboy View Post
    When n=1 we get the first term. That is 13. When n=2 we get sum of 1st 2 terms = 38 Hence 2nd term= 25 So common difference = 12
    That's better than what I said.

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