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In this paper, we consider a general subclass of analytic and bi-univalent functions in the open unit disk in the complex plane. Making use of the Chebyshev polynomials, we obtain upper bound estimate for the second Hankel determinant for…

Complex Variables · Mathematics 2017-02-23 Nizami Mustafa

In this paper, new class of bi-univalent functions are introduced. Upper bound of the second Hankel determinant $|H_2(2)|$ of subclass of bi-univalant functions class $\Sigma$, which defined by subordination, investigated. Furthermore, some…

Complex Variables · Mathematics 2019-08-21 Alaa H. El-Qadeem , Mohamed A. Mamon

In this paper, sharp bounds are established for the second Hankel determinant of logarithmic coefficients for normalised analytic functions satisfying certain differential inequality.

Complex Variables · Mathematics 2022-08-16 Mridula Mundalia , S. Sivaprasad Kumar

The estimates for the second Hankel determinant a_2a_4-a_3^2 of analytic function f(z)=z+a_2 z^2+a_3 z^3+...b for which either zf'(z)/f(z) or 1+zf"(z)/f'(z) is subordinate to certain analytic function are investigated. The estimates for the…

Complex Variables · Mathematics 2013-03-04 Lee See Keong , V. Ravichandran , Shamani Supramaniam

We consider a family of all analytic and univalent functions (i.e., one-to-one) in the unit disk $\mathbb{D}:=\{z\in \mathbb{C}:|z|<1\}$ of the form $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper, we obtain the sharp bounds of the second…

Complex Variables · Mathematics 2021-12-09 Vasudevarao Allu , Vibhuti Arora

Making use of Chebyshev polynomials, we obtain upper bound estimate for the second Hankel determinant of a subclass $\mathcal{N}_{\sigma }^{\mu}\left( \lambda ,t\right) $ of bi-univalent function class $\sigma.$

Complex Variables · Mathematics 2017-11-21 H. Orhan , N. Magesh , V. K. Balaji

Let $f$ be analytic in the unit disk $\mathbb D$ and normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper, we give upper bounds of the Hankel determinant of second order for the classes of starlike functions of order $\alpha$,…

Complex Variables · Mathematics 2019-12-30 Milutin Obradovic , Nikola Tuneski

In this paper we determine the upper bounds of $|H_{2}(3)|$ for the inverse functions of functions of some classes of univalent functions, where $H_{2}(3)(f)=a_{3}a_{5}-a_{4}^{2}$ is the Hankel determinant of a special type.

Complex Variables · Mathematics 2022-11-23 Milutin Obradović , Nikola Tuneski

In this paper, we investigate the sharp bounds of the second Hankel determinant of Logarithmic coefficients for the starlike and convex functions with respect to symmetric points in the open unit disk.

Complex Variables · Mathematics 2021-12-07 Vasudeavarao Allu , Vibhuti Arora , Amal Shaji

In this paper our purpose is to find upper bound estimate for the second Hankel determinant $|a_{2}a_{4}-a_{3}^{2}|$ for functions defined by convolution belonging to the class $\mathcal{N}_{\sigma}^{\mu,\delta}(\lambda,t)$ by using…

Complex Variables · Mathematics 2017-07-11 Halit Orhan , Evrim Toklu , Ekrem Kadıoğlu

In this paper we give the upper bounds of the Hankel determinants of the second and third order for the class $\mathcal{S}$ of univalent functions in the unit disc.

Complex Variables · Mathematics 2019-12-16 Milutin Obradović , Nikola Tuneski

In this paper, we consider the class of strongly bi-close-to-convex functions of order $\alpha$ and bi-close-to-convex functions of order $\beta$. We obtain an upper bound estimate for the second Hankel determinant for functions belonging…

Complex Variables · Mathematics 2021-03-30 S. Kanas , V. Sivasankari , O. Karthiyayini , S. Sivasubramanian

The aim of this paper is to obtain an upper bound to the second Hankel the determinant for starlike and convex functions of order.

Complex Variables · Mathematics 2019-03-28 A. A. Amourah , Anas Aljarah , M. Darus

In this paper we determine the upper bounds of the Hankel determinants of special type $H_{2}(3)(f)$ and $H_{2}(4)(f)$ for the class of univalent functions and for the class $\mathcal{U}$ defined by \[ \mathcal{U}=\left\{ f\in\mathcal{A} :…

Complex Variables · Mathematics 2022-12-14 Milutin Obradović , Nikola Tuneski

In the present investigation the authors obtain upper bounds for the second Hankel determinant of the classes bi-starlike and bi-convex functions of order beta.

Complex Variables · Mathematics 2015-10-08 Erhan Deniz , Murat Çağlar , Halit Orhan

In this sequel to the recent work (see Azizi et al., 2015), we investigate a subclass of analytic and bi-univalent functions in the open unit disk. We obtain bounds for initial coefficients, the Fekete-Szeg\"o inequality and the second…

Complex Variables · Mathematics 2015-09-18 N. Magesh , J. Yamini

In this paper we give improved, probably not sharp, upper bounds of the Hankel determinant of third order for various classes of univalent functions and conjecture the sharp one.

Complex Variables · Mathematics 2020-10-09 Milutin Obradovic , Nikola Tuneski

Let $f$ be analutic in the unit disk $\mathbb D$ and normalized so that $f(z)=z+a_2z^2+a_3z^3+\cdots$. In this paper we give sharp bound of Hankel determinant of the second order for the class of analytic unctions satisfying \[ \left|\arg…

Complex Variables · Mathematics 2019-03-20 Milutin Obradovic , Nikola Tuneski

Using some properties of the Grunsky coefficients we improve earlier results for upper bounds of the Hankel determinants of the second and third order for the class $\mathcal{S}$ of univalent functions.

Complex Variables · Mathematics 2024-11-20 Milutin Obradović , Nikola Tuneski

In this paper we improve the bounds of the third order Hankel determinant for two classes of univalent functions with bounded turning. The bounds are not sharp, but the sharp ones are conjectured.

Complex Variables · Mathematics 2020-10-28 Milutin Obradović , Nikola Tuneski , Pawel Zaprawa
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