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On Certain Subclass of Starlike Functions with Two Fixed Points


Affiliations
1 Department of Mathematics, Vellore Institute of Technology, Deemed University, Vellore-632 014, TN, India
     

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Let STλ(n, α, z0) be the class of functions o f the form

                              f(z) = a1z-Σamzm,

where am ≥ 0 and a1 > 0, analytic in the unit disc

E = {z :|z| < 1 ) and F(z) = 2/z∫ f(t)dt

satisfying (1-λ) F(Z0)/Z0 + λF'(Z0) = 1; 0≤λ≤1, -1<Z0<1.

such that Re {Dn+1f(Z)/Dnf(Z)} > α|Dn+1f(Z)/Dnf(Z)-1|, α≥0

where D is the Ruscheweyh derivative o f f(Z). Properties of functions in STλ(n, α Z0) such as coefficient estimate, closure theorem, extreme points and radius of convexity are determined.


Keywords

Univalent, Starlike, Convex, Extreme Points.
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  • On Certain Subclass of Starlike Functions with Two Fixed Points

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Authors

G. Murugusundaramoorthy
Department of Mathematics, Vellore Institute of Technology, Deemed University, Vellore-632 014, TN, India
K. Vijaya
Department of Mathematics, Vellore Institute of Technology, Deemed University, Vellore-632 014, TN, India

Abstract


Let STλ(n, α, z0) be the class of functions o f the form

                              f(z) = a1z-Σamzm,

where am ≥ 0 and a1 > 0, analytic in the unit disc

E = {z :|z| < 1 ) and F(z) = 2/z∫ f(t)dt

satisfying (1-λ) F(Z0)/Z0 + λF'(Z0) = 1; 0≤λ≤1, -1<Z0<1.

such that Re {Dn+1f(Z)/Dnf(Z)} > α|Dn+1f(Z)/Dnf(Z)-1|, α≥0

where D is the Ruscheweyh derivative o f f(Z). Properties of functions in STλ(n, α Z0) such as coefficient estimate, closure theorem, extreme points and radius of convexity are determined.


Keywords


Univalent, Starlike, Convex, Extreme Points.