# Joseph-Louis Lagrange

### Renounced Physicist

"Before we take to sea we walk on land, Before we create we must understand"

## History

Joseph-Louis Lagrange was born in Turin, Italy on January 25, 1736. He died on April 10, 1813 in Paris, France. His father wanted him to be a lawyer, but Lagrange had a personal interest in mathematics and astronomy. At 16 he began studying mathematics on his own. By age 19, he had been appointed a professorship at the Royal Artillery School in Turin.

## Summary of Contributions to Pysics

Joseph-Louis Lagrange extended the method of taking possible constraints into account, called Lagrange multipliers. The method of Lagrange multipliers is a strategy for finding the local maxima and minimal of a function subject to equality constraints. Lagrange also invented the method of solving differential equations known as variation of parameters. The variation of parameters is a general method to solve inhomogeneous linear ordinary differential equations. Which is an equation containing a function of one independent variable and its derivatives. Finally, Lagrange proved that every natural number is a sum of four squares called Lagrange's four square theorem. This theorem states that every natural can be represented as the sum of four integer squares using the equation P = (a not)^2 + (a one)^2 + (a two)^2 + (a three)^2.