Analytical solution of polynomial equations with an application to the Quintic equation

摘要

A recently proposed method for the derivation of exact analytical integral formulae for the zeros of analytic functions (based on the simple discontinuity problem for a sectionally analytic function along the real axis) is applied here to the case of polynomials. The peculiarity of the present application is that the integrals appearing in the closed-form formulae for the sought zeros are interpreted as Cauchy-type principal-value integrals or even as finite-part integrals. The case of the quintic equation with real coefficients is considered in some detail, and it is shown that the roots of this equation can always be obtained in closed form. Numerical results for this equation are also presented. Equations of higher degree can also be solved in closed form under appropriate conditions.