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Hankel determinant for certain class of analytic function defined by generalized derivative operator
Author(s) -
Ma′moun Harayzeh Al-Abbadi,
Maslina Darus
Publication year - 2012
Publication title -
tamkang journal of mathematics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.324
H-Index - 18
eISSN - 0049-2930
pISSN - 2073-9826
DOI - 10.5556/j.tkjm.43.2012.517
Subject(s) - lambda , mathematics , operator (biology) , combinatorics , function (biology) , physics , quantum mechanics , biochemistry , chemistry , repressor , evolutionary biology , biology , transcription factor , gene

The authors in cite{mam1} have recently introduced a new generalised derivatives operator $ mu_{lambda _1 ,lambda _2 }^{n,m},$ which generalised many well-known operators studied earlier by many different authors. By making use of the generalised derivative operator $mu_{lambda _1 ,lambda _2 }^{n,m}$, the authors derive the class of function denoted by $ mathcal{H}_{lambda _1 ,lambda _2 }^{n,m}$, which contain normalised analytic univalent functions $f$ defined on the open unit disc $U=left{{z,inmathbb{C}:,left| z ight|,<,1} ight}$ and satisfy egin{equation*} {mathop{m Re}olimits} left( {mu _{lambda _1 ,lambda _2 }^{n,m} f(z)} ight)^prime > 0(z in U). end{equation*} This paper focuses on attaining sharp upper bound for the functional $left| {a_2 a_4 - a_3^2 } ight|$ for functions $f(z)=z+ sumlimits_{k = 2}^infty {a_k ,z^k }$ belonging to the class $mathcal{H}_{lambda _1 ,lambda _2 }^{n,m}$.

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