How to prove (p-1) = -1 (mod p), p is a prime.

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SUMMARY

The discussion centers on proving the equation (p-1)! ≡ -1 (mod p) for prime numbers p. Participants emphasize the importance of understanding the concept of inverses within modular arithmetic, specifically how each element a in the system has an inverse a^-1 such that a * a^-1 ≡ 1 (mod p). The reference to Wilson's theorem provides a foundational proof for this relationship, confirming that the factorial of (p-1) modulo p yields -1.

PREREQUISITES
  • Understanding of modular arithmetic
  • Familiarity with factorial notation
  • Knowledge of Wilson's theorem
  • Basic group theory concepts, particularly regarding inverses
NEXT STEPS
  • Study Wilson's theorem in detail to grasp its implications on prime numbers
  • Explore modular arithmetic properties and their applications
  • Investigate group theory, focusing on the concept of inverses
  • Practice solving modular equations involving factorials
USEFUL FOR

This discussion is beneficial for mathematicians, students studying number theory, and anyone interested in advanced modular arithmetic concepts.

lifom
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(p-1)! = -1(mod p), where p is a prime
I have tried small values of p but I can't find any pattern. Can anyone give me some hints or directions? I don't know a detail proof. Thank you
 
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The matter turns on inverses. For every a in the system there is an a^-1, such that a*a^-1 = 1. (Generally that is an axiom of the group property.)
 

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