Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions

Abstract In this study, for 0 < q < 1 $0< q<1$ , we first introduce a function φ q ( τ ) = e q τ − 1 q ( 1 − q τ ) $\varphi _{q}\left ( \tau \right ) = \frac{e^{q\tau }-1}{q\left ( 1-q\tau \right ) }$ and prove that φ q ( τ ) $\varphi _{q}\left ( \tau \right ) $ is convex univalent in th...

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Main Authors: Mohammad Faisal Khan, Mohammed Abaoud
Format: Article
Language:English
Published: SpringerOpen 2025-08-01
Series:Journal of Inequalities and Applications
Subjects:
Online Access:https://doi.org/10.1186/s13660-025-03337-z
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author Mohammad Faisal Khan
Mohammed Abaoud
author_facet Mohammad Faisal Khan
Mohammed Abaoud
author_sort Mohammad Faisal Khan
collection DOAJ
description Abstract In this study, for 0 < q < 1 $0< q<1$ , we first introduce a function φ q ( τ ) = e q τ − 1 q ( 1 − q τ ) $\varphi _{q}\left ( \tau \right ) = \frac{e^{q\tau }-1}{q\left ( 1-q\tau \right ) }$ and prove that φ q ( τ ) $\varphi _{q}\left ( \tau \right ) $ is convex univalent in the open unit disk U $\mathcal{U}$ for all q ∈ ( 0 , 0.32 ) $q\in \left ( 0,0.32\right ) $ . Further, using the subordination technique and considering q-difference operator, we define a new subclass S φ ∗ ( q ) $S_{\varphi }^{\ast }(q)$ of q-starlike functions associated with a function 1 + φ q ( τ ) $1+\varphi _{q}\left ( \tau \right ) $ , which is in the class P $\mathcal{P}$ . Some new geometric properties, such as coefficient bounds, Feketo–Szego inequalities, and the upper bound of the second-order Hankel determinant, are investigated for the function h belonging to the class S φ ∗ ( q ) $S_{\varphi }^{\ast }(q)$ .
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spelling doaj-art-78f41fda9543458593bf391d959e90b62025-08-20T04:02:41ZengSpringerOpenJournal of Inequalities and Applications1029-242X2025-08-012025111310.1186/s13660-025-03337-zCoefficient inequalities and Hankel determinant for a new subclass of q-starlike functionsMohammad Faisal Khan0Mohammed Abaoud1Department of Basic Sciences, College of Science, and Theoretical Studies, Saudi Electronic UniversityDepartment of Mathematics and Statistics, Imam Mohammad Ibn Saud Islamic University (IMSIU)Abstract In this study, for 0 < q < 1 $0< q<1$ , we first introduce a function φ q ( τ ) = e q τ − 1 q ( 1 − q τ ) $\varphi _{q}\left ( \tau \right ) = \frac{e^{q\tau }-1}{q\left ( 1-q\tau \right ) }$ and prove that φ q ( τ ) $\varphi _{q}\left ( \tau \right ) $ is convex univalent in the open unit disk U $\mathcal{U}$ for all q ∈ ( 0 , 0.32 ) $q\in \left ( 0,0.32\right ) $ . Further, using the subordination technique and considering q-difference operator, we define a new subclass S φ ∗ ( q ) $S_{\varphi }^{\ast }(q)$ of q-starlike functions associated with a function 1 + φ q ( τ ) $1+\varphi _{q}\left ( \tau \right ) $ , which is in the class P $\mathcal{P}$ . Some new geometric properties, such as coefficient bounds, Feketo–Szego inequalities, and the upper bound of the second-order Hankel determinant, are investigated for the function h belonging to the class S φ ∗ ( q ) $S_{\varphi }^{\ast }(q)$ .https://doi.org/10.1186/s13660-025-03337-zAnalytic and univalent functionsHankel determinantq-Starlike functionsSubordination
spellingShingle Mohammad Faisal Khan
Mohammed Abaoud
Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions
Journal of Inequalities and Applications
Analytic and univalent functions
Hankel determinant
q-Starlike functions
Subordination
title Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions
title_full Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions
title_fullStr Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions
title_full_unstemmed Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions
title_short Coefficient inequalities and Hankel determinant for a new subclass of q-starlike functions
title_sort coefficient inequalities and hankel determinant for a new subclass of q starlike functions
topic Analytic and univalent functions
Hankel determinant
q-Starlike functions
Subordination
url https://doi.org/10.1186/s13660-025-03337-z
work_keys_str_mv AT mohammadfaisalkhan coefficientinequalitiesandhankeldeterminantforanewsubclassofqstarlikefunctions
AT mohammedabaoud coefficientinequalitiesandhankeldeterminantforanewsubclassofqstarlikefunctions