Albert Girard

French mathematician

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June 29, 2026

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Albert Girard was a French mathematician who made a significant contribution to algebra. In 1629, he suggested the fundamental theorem of algebra, which states that every polynomial equation of degree n with complex coefficients has n complex roots. This theorem was crucial in establishing the concept of complex numbers as legitimate mathematical entities and helped consolidate algebra as a discipline. While Girard's work was foundational, the first complete proof of the theorem was later provided by Carl Friedrich Gauss.1

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Fibonacci
Fibonacci sequence
…formula by the French-born mathematician Albert Girard in 1634: u_{n + 2} = u_{n + 1} + u_n, in which u represents the term and the subscript its rank in the sequence. The mathematician Robert Simson at the University of Glasgow in 1753 noted that, as the numbers increased in…
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…formula by the French-born mathematician Albert Girard in 1634: u_{n + 2} = u_{n + 1} + u_n, in which u represents the term and the subscript its rank in the sequence. The mathematician Robert Simson at the University of Glasgow in 1753 noted that, as the numbers increased in…
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algebra
The fundamental theorem of algebra
…suggested by the French-born mathematician Albert Girard in 1629, and which asserts that every polynomial with real number coefficients could be expressed as the product of linear and quadratic real number factors or, alternatively, that every polynomial equation of degree n with complex coefficients had n complex roots. For example,…
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…suggested by the French-born mathematician Albert Girard in 1629, and which asserts that every polynomial with real number coefficients could be expressed as the product of linear and quadratic real number factors or, alternatively, that every polynomial equation of degree n with complex coefficients had n complex roots. For example,…
Read More