ABK

Members
  • Content count

    1
  • Joined

  • Last visited


Community Reputation

0

About ABK

  • Rank
    Newbie

ABK's Activity

  1. ABK added an answer to a question Math - Prime number   

    My first approach was to consider modulo 6.

    Assume a > 6, Since a is prime we have a=1, -1 (mod 6)

    Thus, a2=1 (mod 6).

    We know, 26 = 2 (mod 6)

    Therefore a2+26=3 (mod 6)

    So any prime greater than 6 would be resulting in a number which is divisible by 3 which NOT prime as required.

    So we have to check 2, 3 and 5 which are the only primes less than 6. It is easy to see that each would yield a non-prime in a2+26. So we're done!
    • 0