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Math Help - Arithmetic Sequence Question

  1. #1
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    Arithmetic Sequence Question

    Hi this is a Question about AP I've been having trouble about, help would be appreciated.

    Q)- The 4th, 6th, and 8th terms of an AP add up to -6. Find the sixth term.

    Help would be tremendously appreciated!
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  2. #2
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    Quote Originally Posted by SeaNanners View Post
    Hi this is a Question about AP I've been having trouble about, help would be appreciated.

    Q)- The 4th, 6th, and 8th terms of an AP add up to -6. Find the sixth term.

    Help would be tremendously appreciated!
    t_n = a + (n-1)d.

    Therefore (a + 3d) + (a + 5d) + (a + 7d) = -6 \Rightarrow a + 5d = t_6 = ......
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  3. #3
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    A slightly different way- since we are asked specifically for the sixth term, call that "a". Then, with "r" as the common difference, the fourth term is a- 2r and the 8th term is a+ 2r. Add those together and you will see that the "2r" terms cancel!
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