Prove, for any non-zero polynomial p, that congruence modulo p is an equivalence relation.
((a)) It is reflexive: f≡fmodp.
((b)) It is symmetric: if f≡gmodp, then g≡fmodp.
((c)) It is transitive: if f≡gmodp and g≡hmodp, then f≡hmodp.
(Definition: If f, g, and p are polynomials over the field F with p=0, we say that f is congruent to g modulo p if (f−g) is divisible by p. If f is congruent to g modulo p, we write f≡gmodp.)