If R is a commutative ring, a polynomial f(x) in R[x] is said to annihilate R if f(a) = 0 for every a belonging to R
Show that x^p - x annihilates Zp (Z is integers)
By Fermat's theorem, if p is a prime, then x^(p-1)=1 (mod p) for any x in Zp. So ...
An annihilator is identified.