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Proof of composites

  1. Oct 2, 2008 #1
    Prove that if p [tex]\geq[/tex] 5 is prime, then p[tex]^{2}[/tex] +2 is composite
    (hint: work mod 3 and use #5 to show p^2 + 2 has a factor of 3.)
     
  2. jcsd
  3. Oct 2, 2008 #2

    tiny-tim

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    Hi phyguy321! :smile:

    Show us what you've tried, and where you're stuck, and then we'll know how to help. :smile:

    (and … erm … what's #5? :redface:)
     
  4. Oct 3, 2008 #3
    The problem is i have no idea of where to start. Modular arithmetic makes no sense to me. and #5 was my other post on modular arithmetic
     
  5. Oct 3, 2008 #4

    tiny-tim

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    Your other post was to prove that for any integer n, n2 = 0 or 1 (mod 3).

    So n2 + 2 = … ? (mod 3).
     
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