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View Full Version : square root of 1 with mod...how to prove it?


jacquelinek
Oct6-09, 02:25 AM
I know that if n is odd and has k distinct prime factors, then the number of roots, x^2 = 1 (mod n), is equal to 2^k.
However, I don't know how to give a formal proof to it.
I simply want to bypass the generalized form x^2 = a (mod n).
How can I prove it directly?
Thank you.

CRGreathouse
Oct6-09, 09:04 AM
Hmm... assuming it holds mod p^k, you could just CRT the results together.