# Coefficient inequality for a function whose derivative has a positive real part

Aini Janteng, Suzeini Abdul Halim, Maslina Darus

Research output: Contribution to journalArticle

80 Citations (Scopus)

### Abstract

Let R denote the subclass of normalised analytic univalent functions f defined by f(z) = z + Σn =2a nzn and satisfy Re{f′ (z)} > 0 where z ε D = { z : |z| < 1}. The object of the present paper is to introduce the functional |a2a4 - a3 2|. For f ε R we give sharp upper bound for |a2a4 - a 3 2|.

Original language English 50 1-5 5 Journal of Inequalities in Pure and Applied Mathematics 7 2 Published - 2006

### Fingerprint

Coefficient Inequalities
Univalent Functions
Analytic function
Upper bound
Denote
Derivatives
Derivative
Object

### Keywords

• Convex and starlike functions
• Fekete-Szegö functional
• Hankel determinant
• Positive real functions

### ASJC Scopus subject areas

• Mathematics(all)

### Cite this

Coefficient inequality for a function whose derivative has a positive real part. / Janteng, Aini; Halim, Suzeini Abdul; Darus, Maslina.

In: Journal of Inequalities in Pure and Applied Mathematics, Vol. 7, No. 2, 50, 2006, p. 1-5.

Research output: Contribution to journalArticle

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