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Math Help - Geometric sequence help

  1. #1
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    Geometric sequence help

    Find the tenth term of -1,2,-4,...

    how do i find out what r is? do i have to use a1 r^(n-1)?
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  2. #2
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    Quote Originally Posted by NeedHelp18 View Post
    Find the tenth term of -1,2,-4,...

    how do i find out what r is? do i have to use a1 r^(n-1)?
    r = \frac{2}{-1} = \frac{-4}{2} = -2.
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    ok so r = -2

    im lost as to how do u find r...
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    Quote Originally Posted by NeedHelp18 View Post
    ok so r = -2

    im lost as to how do u find r...
    Go back and read my post - I have showed you how. It's the common ratio.
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