Given $17x \equiv 1 \pmod{23}$
How to solve this linear congruence? All hints are welcome.
edit: I know the Euclidean Algorithm and know how to solve the equation $17m+23n=1$ but I don't know how to compute x with the use of m or n.
Answer
To do modular division I do this:
an - bm = c where c is dividend, b is modulo and a is divisor, then n is quotient
17n - 23m = 1
Then using euclidean algorithm, reduce to gcd(a,b) and record each calculation
As described by http://mathworld.wolfram.com/DiophantineEquation.html
17 23 $\quad$ 14 19
17 6 $\quad\;\;$ 14 5
11 6 $\quad\;\;\;\;$ 9 5
5 6 $\quad\;\;\;\;\;$ 4 5
5 1 $\quad\;\;\;\;\;$ 4 1
1 1 $\quad\;\;\;\;\;$ 0 1
Left column is euclidean algorithm, Right column is reverse procedure
Therefore $ 17*19 - 23*14 = 1$, i.e. n=19 and m=14.
The result is that 1/17 ≡ 19 mod 23
this method might not be as quick as the other posts, but this is what I have implemented in code. The others could also be, but I thought I would share my method.
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