JOSEPH LOUIS LAGRANGE was born in Italy of French ancestry on January 25, 1736. He became captived by mathematics at an early age when he read an essay by Halley on Newton’s calculus. At the age of 19, he became a professor of mathematics at the Royal Artillery School in Turin. Lagrange made significant contributions to many branches of mathematics and physics, among them the theory of numbers, the theory of equations, ordinary and partial ifferential equations, the calculus of variations, analytic geometry, fluid dynamics, and celestial mechanics. His methods for solving third- and forth-degree polynomial equations by radicals laid the groundwork for the group-theoretic approach to solving polynomials taken by Galois. Lagrange was a very careful writer with a clear and elegant style.
At the age of 40, Lagrange was appointed Head of the Berlin Academy, succeeding Euler. In offering this appoinment, Frederick The Great proclaimed that the “greatest king in Europe” ougth to have the “greatest mathematician in Europe” at his court. In 1787, Lagrange was invited to Paris by Louis XVI and became a good friend of the king and his wife, Marie Antoinette. In 1793, Lagrange headed a commission, which included Laplace and Lavoisier, to devise a new system of weigth and measures. Out of this came the metric system. Late in his life he was made a count by Napoleon. Lagrange died on April 10, 1813.
(Sumber : Joseph A. Gallian 4th ed)