Integro-differential equations and functional analysis
On real roots of systems of trancendental equations with real coefficients
A. M. Kytmanov,
O. V. Khodos Siberian Federal University, Krasnoyarsk, Russian Federation
Abstract:
The work is devoted to the study of the number of real roots of systems of transcendental equations in
$\mathbb C^n$ with real coefficients, consisting of entire functions, in some bounded multidimensional domain
$D\subset \mathbb R^n$. It is assumed that the number of roots of the system is discrete (then it is no more than countable). For some entire function
$\varphi (z), z\in \mathbb C^n$, with real Taylor coefficients at
$z=0$, and a given system of equations, the concept of a resultant
$R_\varphi(t)$ is introduced, which is an entire function of one complex variable
$t$. It is constructed using power sums of the roots of the system in a negative degree, found using residue integrals. If the resultant has no multiple zeros, then it is shown that the number of real roots of the system in
$D=\{x\in \mathbb R^n: a<\varphi(x)<b\}$ (
$x=\mathrm{Re}\, z $) is equal to the number of real zeros of this resultant in the interval
$(a,b)$. An example is given for a system of equations.
Keywords:
systems of transcendental equations, resultant, simple roots.
UDC:
517.55
MSC: 39B72,
32A05,
32A15,
32A27 Received: 29.02.2024
Revised: 25.04.2024
Accepted: 06.05.2024
DOI:
10.26516/1997-7670.2024.49.90