Solution

ID: past-exam-of-the-mathematics-course-of-the-university-of-cambridge/2024/iii/paper-136/5/b/solution

Let . Its minimal polynomial is , whose discriminant is . Since , the prime does not divide the index , so the Dedekind factorization theorem applies at . In ,
The quadratic factor has discriminant , which is a quadratic nonresidue modulo , so it is irreducible. Therefore
where
Their residue-field degrees are one and two. Both factors of occur with multiplicity one, so both prime-ideal exponents are one. Hence neither nor is ramified.

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