24. Show that (x ^p) − x has p distinct zeros in Zp, for any
prime p. Conclude that (x ^p) − x = x(x − 1)(x − 2)· · ·(x − (p −
1)).
(this is not as simple as showing that each element in
Zp is a root -- after all, we've
seen that in Z6[x], the polynomial
x^2-5x has 4 roots, 0, 5, 2, and 3, but x^2-5 is not equal to
(x-0)(x-5)(x-2)(x-3))