Friday 12 July 2013

elementary number theory - Modulus Congruence

Prove or find a counterexample: Let p be a prime, and a and b positive integers. If a^2 ≡ b^2 (mod p) then a ≡ b (mod p).




I know that: If a and b are integers, we say that they are congruent modulo d iff b − a is a multiple of d. Equivalently, a and b are congruent mod d iff a (mod d) = b (mod d). Rewrite this as: a ≡ b (mod d).



I also know if p is prime, then GCD(a, p) = 1, GCD(b, p) = 1, but I'm not entirely sure if any of this information is useful or not

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