French mathematicians have made outstanding contributions in the field of mathematics. Since modern times, many world-famous mathematicians have emerged in France, such as Descartes, Fermat, Lagrange, Vedas, Mei Sen, Fourier and Laplace. Mathematicians have made important discoveries and theories in different fields, which have promoted the development of mathematics. Vieta theorem is of great significance in junior high school mathematics, and Lagrange is the representative of advanced mathematics.