Question

(a) Use modular arithmetic to show that if an integer a is not divisible by 3,...

(a) Use modular arithmetic to show that if an integer a is not divisible by 3, then a 2 ≡ 1 (mod 3).

(b) Use this result to prove that in any Pythagorean triple (x, y, z), either x or y (or both) must be divisible by 3

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