The natural numbers x, y, z are such that x² + y² + z² is divisible by 9. Prove that one can choose two of these three numbers such that the difference of their squares is also divisible by 9.
📜 Leaflet #modular_arithmetic
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📜 Leaflet #modular_arithmetic
🌐 Wikipedia
✍ Write your answer in the comments!
Wikipedia
Modular arithmetic
system of algebraic operations defined for remainders under division by a fixed positive integer; system of arithmetic for integers, where numbers "wrap around" upon reaching a certain value—the modulus