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

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 |a2| and |a3|, where a2, a3 are the initial Taylor-Maclaurin coefficients. Further we obtain the Fekete-Szego inequalities for this subclass of the bi-univalent function class sigma. We also give several illustrative examples of the bi-univalent functionclass which we introduce here.