have an idea?

[koukou8617]

Recall the definition of n! (read n factorial"):
n! = (n)(n-1)(n-2) ….(2)(1) =?(k)
In both (a) and (b) below, suppose p?3 is prime.
(a) Prove that if x? Zpx is a solution to x square ?1 (mod p), then x ?±1 (mod p).
(b) Prove that (p-1)!?±1 (mod p)

Zpx x shoud be above p

 

[mmm4444bot]

… x ? Zpx …

The symbol that I see between x and Zpx is an open box.

What am I supposed to see there?

 

[koukou8617]

Zpx this x is the symbol of multiplication

 

[galactus]

For part a, this is one of Euler's theorems. \(\displaystyle a^{p-1}\equiv 1(mod \;\ p)\)

For part b, look into Wilson's theorem.

 

[koukou8617]

For part a, this is one of Euler's theorems. \(\displaystyle a^{p-1}\equiv 1(mod \;\ p)\)

For part b, look into Wilson's theorem.

bingo
you are right
i know how to solve it

thank you all guys