Euclid's Algorithm

Find the smallest positive integer solution of 22 x 14 ( m o d 97 ) 22x \equiv 14 \pmod{97}


The answer is 80.

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1 solution

Wesllen Brendo
Aug 23, 2014

Como 22 x 14 ( m o d 97 ) {22x}\equiv 14\pmod{97} , então existe um y y inteiro tal que 22 x 14 = 97 y {22x}-14={97y} ou 22 x 97 y = 14 {22x}-{97y}=14 . Uma equação Diofantina. Assim, pelo algoritmo de Euclides, temos: 97 = 4 × 22 + 9 97=4\times22 +9 \Rightarrow 22 = 2 × 9 + 4 22=2\times9 +4 \Rightarrow 9 = 2 × 4 + 1 9=2\times4 +1 . Daí, 9 2 × 4 = 1 9-2\times4=1 \Rightarrow 9 2 × ( 22 2 × 9 ) = 1 9-2\times(22-2\times9)=1 \Rightarrow 5 × 9 2 × 22 = 1 5\times9 - 2\times22=1 \Rightarrow 5 × ( 97 4 × 22 ) 2 × 22 = 1 5\times(97-4\times22) - 2\times22=1 \Rightarrow 5 × 97 22 × 22 = 1 5\times97 - 22\times22=1 . Segue que, 22 × ( 22 ) 97 × ( 5 ) = 1 22\times(-22) - 97\times(-5)=1 . Multiplicando por 14, temos 22 × ( 308 ) 97 × ( 70 ) = 14 22\times(-308)-97\times(-70)=14 . Assim, ( 308 , 70 ) (-308,-70) é uma solução particular. As outras são da forma x = 308 97 k x=-308-{97k} e y = 70 22 k y=-70-{22k} . Como x > 0 x>0 , segue que 308 97 k > 0 -308-{97k}>0 , ou seja, k 4 k\le-4 . Tomando, então, k = 4 k=-4 , pois é o menor valor que torna x x positivo, obtemos x = 80 x=\boxed{80}

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math man - 6 years, 8 months ago

Please use English if possible. We can't understand it.

Satvik Golechha - 6 years, 8 months ago

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not everyone can speak english @Satvik Golechha and @math man , you can translate it

Mardokay Mosazghi - 6 years, 8 months ago

Satvik, we can write a solution in English....

Aditya Raut - 6 years, 8 months ago

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