Paper 2, Section II, H

Number Fields
Part II, 2015

(i) Let d2d \equiv 2 or 3mod43 \bmod 4. Show that (p)(p) remains prime in OQ(d)\mathcal{O}_{\mathbb{Q}(\sqrt{d})} if and only if x2dx^{2}-d is irreducible modp\bmod p.

(ii) Factorise (2)(2), (3) in OK\mathcal{O}_{K}, when K=Q(14)K=\mathbb{Q}(\sqrt{-14}). Compute the class group of KK.