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Math Help - Help find Sum

  1. #1
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    Help find Sum

    Can someone please help me get this the correct answer is -6026/13
    find the sum of K 12-57

    57
    E(Sum) 7-4k
    k=12 13
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  2. #2
    is up to his old tricks again! Jhevon's Avatar
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    Quote Originally Posted by helpless13 View Post
    Can someone please help me get this the correct answer is -6026/13
    find the sum of K 12-57

    57
    E(Sum) 7-4k
    k=12 13
    i don't understand what you are trying to write. do you mean \sum_{k = 12}^{57} \frac {7 - 4k}{13} ?
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  3. #3
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    Reply

    yes that's what i'm trying to write
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  4. #4
    Grand Panjandrum
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    Quote Originally Posted by helpless13 View Post
    Can someone please help me get this the correct answer is -6026/13
    find the sum of K 12-57

    57
    E(Sum) 7-4k
    k=12 13
    Would that be:

     <br />
\sum_{k=12}^{57} \frac{7-4k}{13}<br />

    This is an arithmatic progression with first term -\ \frac{41}{13} (which corresponds to k=12 ), common difference -\ \frac{4}{13} and with 57-12+1 = 46 terms. You should have a forumla for this.

    RonL
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  5. #5
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    I do have the formula I just cant get the write answer i dont know what im doing wrong
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  6. #6
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    I know you have to take the sum of the first 57 terms and subtract the first 12 but i don't get the correct answer
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  7. #7
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    Thanks

    Alright thanks for your help i got it now
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