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Math Help - divisible by 24

  1. #1
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    divisible by 24

    if n is a prime number greater than 6, then prove that n^2-1 will be divisible by 24.
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  2. #2
    MHF Contributor chisigma's Avatar
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    Recently this topic has been treated here...

    http://www.mathhelpforum.com/math-he...er-theory.html

    If p is an odd number grater than 5 non multiple of 3, p^2-1 is divisible by 24...

    Kind regards

    \chi \sigma
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  3. #3
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    Consider the fact that n^2-1=(n+1)(n-1). Now consider the divisibility of n+1 and n-1 by 3, 2, and 4, using the fact that n is a prime greater than 3, and so is odd and not divisible by 3.

    --Kevin C.
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