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JMB Journal of Microbiolog and Biotechnology

OPEN ACCESS eISSN 0454-8124
pISSN 1225-6951
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Original Article

Kyungpook Mathematical Journal 2010; 50(1): 37-47

Published online March 23, 2010

Copyright © Kyungpook Mathematical Journal.

The Fekete-Szegö Problem for a Generalized Subclass of Analytic Functions

Erhan Deniz, Halit Orhan

Department of Mathematics, Faculty of Science, Ataturk University, 25240 Erzu- rum, Turkey

Received: March 23, 2010; Revised: March 23, 2010; Accepted: March 23, 2010

Abstract

In this present work, the authors obtain Fekete-Szegö inequality for certain normalized analytic function $f(z)$ defined on the open unit disk for which $frac{(1-alpha )z(D_{lambda, mu }^{m}f(z))^{prime }+alpha z(D_{lambda, mu }^{m+1}f(z))^{prime }}{% (1-alpha )D_{lambda, mu }^{m}f(z)+alpha D_{lambda, mu }^{m+1}f(z)}$ $(lambda geq mu geq 0,$ $min {mathbb{N}}_{0},$} $alpha geq 0) $ lies in a region starlike with respect to 1 and is symmetric with respect to the real axis. Also certain applications of the main result for a class of functions defined by Hadamard product (or convolution) are given. As a special case of this result, Fekete-Szegö inequality for a class of functions defined through fractional derivatives is obtained. The motivation of this paper is to generalize the Fekete-Szegö inequalities obtained by Srivastava et al., Orhan et al. and Shanmugam et al, by making use of the generalized differential operator $D_{lambda, mu }^{m}.$

Keywords: Fekete-Szegö, problem, Analytic functions, Hadamard product, Starlike functions