AIMS Mathematics, 2018, 3(4): 600-607. doi: 10.3934/Math.2018.4.600

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The norm of pre-Schwarzian derivative on subclasses of bi-univalent functions

1 School of Liberal Studies, Ambedkar University Delhi, 110006, Delhi
2 Department of Mathematics, AMITY School of Applied Science, AMITY University, 302003, Rajasthan

In the present paper, we give the best estimates for the norm of pre-Schwarzian derivatives $||{T_f}(z)|| = \mathop {\sup }\limits_{|z| < 1} (1 - |z{|^2})\left| {\frac{{f''(z)}}{{f'(z)}}} \right|$ for subclasses of bi-univalent functions.
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