Proving with Congruence of intergers

  1. It just how do i prove that

    b^3 +b^2 +1 does not divide by 5

    Im thinking this way,
    cause i know that b^3 +b^2 +1 is not congruent to 0(mod5)

    therefore we use contradition to prove it. im just not sure how to use contradition? or maybe im looking at this in a completely bad light? maybe there is another method?
  2. jcsd
  3. This can be worked out by considering all the cases from 0 to 4 mod 5.
  4. Mark44

    Staff: Mentor

    Double posted.
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