A concrete radical extension with group S3
Research context
postgraduate concept · established · As of 2026-10-10
For x³−2 over Q, the splitting field is Q(cube-root(2),zeta-3), has degree six and Galois group S3.
Key knowledge
For x³−2 over Q, the splitting field is Q(cube-root(2),zeta-3), has degree six and Galois group S3. The cubic is Eisenstein at two; its real cubic field does not contain the nonreal primitive cube root of unity. S3 has normal subgroup A3 with cyclic quotient of order two, so this extension is solvable by radicals although its Galois group is nonabelian.
Conditions and scope
- The base field is Q; zeta-3=e^(2pi i/3). All three roots are adjoined in the splitting field. This worked derivation applies Milne's cubic splitting and group criteria: the discriminant is −108, a nonsquare in Q, so the group is S3.
- A nonabelian Galois group need not be nonsolvable.
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References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Author checked this English statement, displayed equation where present and stated hypotheses against these source locations: Examples 2.6/2.10 p.29: cubic splitting fields and roots; Example 3.8 p.37: x-cubed minus2 nonnormal real field; Example 4.7 p.49: cubic A3/S3 criterion, applied in the recorded worked example; cyclotomic extensions pp.64–66; solvability Theorem 5.34 pp.76–80. The check is bounded to the recorded claims; no complete proof reconstruction, software proof replay or universal literature completeness is claimed.
2026-10-10 · Author source-body/statement/equation/domain check, with graph associations scoped individually. Separate independent content/source/inventory review is required before branch closure.
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