Solving the 'quadratic congruence equation'...
(1)
... is equivalent to find two integers x < p and y so that is...
(2)
Now if satisfies (2) for some y, then satisfies also (2) for some other y...
Kind regards
This is from chapter on linear congruences:
Show that if p is an odd prime and a is a positive integer not divisible by p, then the congruence has either no solution or exactly two incongruent solutions.
I can see If , then there are no solutions. I'm really not sure how to approach the rest of this...