Axe? +bx+c=0，a≠0

x 1=[-b-√(b？ -4ac)]/(2a)

x2=[-b+√(b？ -4ac)]/(2a)

Vieta's theorem is:

x 1+x2=-b/a

x 1*x2=c/a

Development history:

Francois Viete, a French mathematician, improved the solutions of cubic and quartic equations in his book On the Identification and Revision of Equations, and established the relationship between the roots and coefficients of equations when n=2 and 3, which is the modern Vieta theorem. ?

David first discovered this relationship between the roots and coefficients of algebraic equations, so people called this relationship Vieta Theorem. David got this theorem in16th century. The proof of this theorem depends on the basic theorem of algebra, but the basic theorem of algebra was first discussed by Gauss in 1799.