THE FEKETE-SZEGO PROBLEMS FOR SUBCLASS OF BI-UNIVALENT FUNCTIONS ASSOCIATED WITH SIGMOID FUNCTION

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Orhan H., Murugusundaramoorthy G., Caglar M.

FACTA UNIVERSITATIS-SERIES MATHEMATICS AND INFORMATICS, vol.37, no.3, pp.495-506, 2022 (ESCI) identifier

  • Publication Type: Article / Article
  • Volume: 37 Issue: 3
  • Publication Date: 2022
  • Doi Number: 10.22190/fumi201022034o
  • Journal Name: FACTA UNIVERSITATIS-SERIES MATHEMATICS AND INFORMATICS
  • Journal Indexes: Emerging Sources Citation Index (ESCI)
  • Page Numbers: pp.495-506
  • Keywords: Analytic functions, univalent functions, bi-univalent functions, Sigmoid function, upper bounds, Fekete-Szego problem, subordination between analytic functions
  • Ataturk University Affiliated: Yes

Abstract

The purpose of this article is to introduce a new subclass of analytic and bi-univalent functions, in associated with sigmoid function and to investigate the upper bounds for |a(2)| and |a(3)|, where a(2), a(3) are the initial Taylor-Maclaurin coefficients. Further, we obtain the Fekete-Szego 5 inequalities for this subclass of the bi-univalent function class sigma. We also give several illustrative examples of the bi-univalent function class which we introduce here.