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JOURNALS // Izvestiya Vysshikh Uchebnykh Zavedenii. Matematika // Archive

Izv. Vyssh. Uchebn. Zaved. Mat., 2022 Number 3, Pages 13–20 (Mi ivm9755)

On Visser's inequality concerning coefficient estimates for a polynomial

S. Gulzara, N. A. Ratherb, M. Sh. Wanib

a Government College for Engineering and Technology, India
b University of Kashmir, Srinagar-190006, India

Abstract: If $P(z)=\sum\limits_{j=0}^{n}a_jz^j$ is a polynomial of degree $n$ having no zero in $|z|<1,$ then it was recently proved that for every $p\in[0,+\infty]$ and $s=0,1,\ldots,n-1,$
\begin{align*} \left\|a_nz+\frac{a_s}{\binom{n}{s}}\right\|_{p}\leq \frac{\left\|z+\delta_{0s}\right\|_p}{\left\|1+z\right\|_p}\left\|P\right\|_{p}, \end{align*}
where $\delta_{0s}$ is the Kronecker delta. In this paper, we consider the class of polynomials having no zero in $|z|<\rho,$ $\rho\geq 1$ and obtain some generalizations of above inequality.

Keywords: polynomial, Visser's inequality, inequality in the complex domain.

UDC: 517

Received: 15.04.2021
Revised: 04.07.2021
Accepted: 29.09.2021

DOI: 10.26907/0021-3446-2022-3-13-20


 English version:
Russian Mathematics (Izvestiya VUZ. Matematika), 2022, 66:3, 9–15


© Steklov Math. Inst. of RAS, 2024