The Second Hankel Determinant Problem for a Class of Bi-Close-to-Convex Functions

Nak Eun Cho, Ebrahim Analouei Adegani, Serap Bulut, Ahmad Motamednezhad
2019 Mathematics  
The purpose of the present work is to determine a bound for the functional H 2 ( 2 ) = a 2 a 4 − a 3 2 for functions belonging to the class C Σ of bi-close-to-convex functions. The main result presented here provides much improved estimation compared with the previous result by means of different proof methods than those used by others.
doi:10.3390/math7100986 fatcat:dm27n5kgfvcqplgqo2pxdg2scq