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Theorem

Fundamental Theorem of Algebra

Also Known As d'Alembert-Gauss Theorem
Algebra

Guarantees that the complex numbers are, in a precise sense, complete enough for algebra: no equation solvable in principle needs a still larger number system than the complex numbers to find its roots. Several mathematicians, including d'Alembert and Euler, attempted proofs earlier in the eighteenth century, but each had gaps; Carl Friedrich Gauss's 1799 doctoral dissertation gave the first substantially rigorous proof, and he returned to give three further, increasingly rigorous proofs over his career.

Facts
Statement
Every non-constant single-variable polynomial with complex coefficients has at least one root in the complex numbers. 1
Proof Year
1799 1
Gauss's 1799 doctoral dissertation gave the first substantially rigorous proof; earlier eighteenth century attempts by d'Alembert (1746) and Euler had gaps a fully rigorous treatment had to close.
Classification
Statement Form
Existence Theorem 1
Statement Form
Inequality 1
FAQs

Who gets the credit for the first proof of the Fundamental Theorem of Algebra?

Gauss is usually credited, from his 1799 doctoral thesis.

Carl Friedrich Gauss is usually credited with the first proof. He presented it in his doctoral thesis of 1799, together with his objections to the other proofs that had been offered before it. Credit is a matter of judgment here, because earlier mathematicians had made serious attempts, so the usual attribution to Gauss reflects how his objections and his own argument are remembered.
Connections

Associated With

Polynomial, Concepts

Has Statement Form

In Branch

Source MacTutor History of Mathematics Archive
Additional Source Fundamental Theorem of Algebra (Wikipedia)History section

Proved By

Source MacTutor History of Mathematics Archive
Additional Source Fundamental Theorem of Algebra (Wikipedia)History section
Sources
1. MacTutor History of Mathematics Archive
University of St Andrews, School of Mathematics and StatisticsView the Source
Fundamental Theorem of Algebra (Wikipedia)
Wikimedia Foundation
  • History
    The first rigorous proof was published by Argand, an amateur mathematician, in 1806 (and revisited in 1813).
  • Proved By: Carl Friedrich Gauss, History section
    The other one was published by Gauss in 1799 and it was mainly geometric, but it had a topological gap, only filled by Alexander Ostrowski in 1920
  • In Branch: Algebra, History section
    it was named when algebra was synonymous with the theory of equations
  • In Group: Polynomials and Elementary Algebra, Lead section
    theorem, states that every non-constant single-variable polynomial with complex coefficients has at least one complex
View the Source
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