Mathematician:Joseph Louis Lagrange

Joseph Lagrange did the following:
 * Author of "Réflexions sur la résolution algébrique des equations" (1770), a complete restudy of all the known methods of solving the cubic and quartic equations.
 * Proposed a prime number as the universally adopted number base. Thus every systematic fraction would be reducible and represent the number in a unique way.
 * Established some very general theorems on whether a number if prime from examining its digits.
 * Tried in vain to prove Fermat's Last Theorem.
 * One of the few exceptions of his time who was doubtful that a polynomial equation of degree greater than four was capable of a formal solution by means of radicals.
 * Gave an insufficient proof of the Fundamental Theorem of Algebra.

He also proved Wilson's Theorem.

Nationality
French

History

 * Born: 1736
 * Died: 1813

Theorems

 * Lagrange's Theorem (Number Theory)
 * Lagrange's Theorem (Group Theory)
 * Lagrange's Identity
 * Lagrange's Four Square Theorem
 * Wilson's Theorem


 * Lagrange's Theorem (Group Theory) was named after him, although he did not prove the general form. What he actually proved was that if a polynomial in $$n$$ variables has its variables permuted in all $$n!$$ ways, the number of different polynomials that are obtained is always a divisor of $$n!$$.

Books and Papers

 * "Réflexions sur la résolution algébrique des equations" (1770), a complete restudy of all the known methods of solving the cubic and quartic equations.