Extension of Nunokawa Lemma for Functions with Fixed Second Coefficient and Its Applications. (27th July 2021)

• Record Type: Journal Article
• Authors: Amani, Mostafa; Aghalary, Rasoul; Ebadian, Ali
• Other Names: Urbina Wilfredo Academic Editor.
• Is Part Of: Journal of function spaces. Volume 2021(2021)
• Publication Date: 2021-07-27
• Subjects: Function spaces -- Periodicals; 515.7305
• DOI: 10.1155/2021/4564694
• Languages: English
• ISSNs: 2314-8896

Abstract

Abstract : In this paper, we study some properties of analytic functions with fixed initial coefficients. The methodology of differential subordination is used for modification and improvements of several well-known results for subclasses of univalent functions by restricting the functions with fixed initial coefficients. Actually, by extending the Nunokawa lemma for fixed initial coefficient functions, we obtain some novel results on subclasses of univalent functions, such as differential inequalities for univalency or starlikeness of analytic functions. Also, we provide some new sufficient conditions for strongly starlike functions. The results of this paper extend and improve the previously known results by considering functions with fixed second coefficients.