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Bibliographic Details
Main Authors: Bland, Jason, Garibaldi, Skip, Rosenberg, Joel
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.25992
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Table of Contents:
  • An observation by J-P. Serre implies that cubic polynomials are unique among generic monic polynomials of degree 2 or higher in that they have a root that is a power series in the discriminant of the polynomial. We provide formulas for this root of a cubic that work in any characteristic. In the special case of a cubic real polynomial with positive discriminant, the series converges and therefore provides an explicit formula for a root; when that polynomial is depressed, the root we provide is the longest root. The proofs are a combination of elementary techniques from algebra, combinatorics, and analysis and employ the notion of a field with an absolute value.