-- Apr 4 In-Class Exercise Thread
If ax = b(mod n) either has d distinct solutions modulo n or no solutions:
where d = gcd(a,n)
For 5x=3mod15:
d = gcd(5,15) = 5
for the solution to be 5 => gcd(a,n)|b
but 5 does not divide 3. So, there is no solution.
For 10x=5mod15:
d = gcd(10,15) = 5
for the solution to be 5 => gcd(a,n)|b
5 divides 10. Hence the following are the solutions:
solutions are 2,5,8,11,14
(
Edited: 2018-04-04)
If ax = b(mod n) either has d distinct solutions modulo n or no solutions:
where d = gcd(a,n)
For 5x=3mod15:
d = gcd(5,15) = 5
for the solution to be 5 => gcd(a,n)|b
but 5 does not divide 3. So, there is no solution.
For 10x=5mod15:
d = gcd(10,15) = 5
for the solution to be 5 => gcd(a,n)|b
5 divides 10. Hence the following are the solutions:
solutions are 2,5,8,11,14