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

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Cho N. E., Adegani E. A., Bulut S., Motamednezhad A.

MATHEMATICS, vol.7, 2019 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 7
  • Publication Date: 2019
  • Doi Number: 10.3390/math7100986
  • Journal Name: MATHEMATICS
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Kocaeli University Affiliated: Yes


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-Sigma 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.