Third order hankel determinant for certain univalent functions

Abstract

The estimate of third Hankel determinant (formula presented) of the analytic function f (z) = z + a2Z2 + a3Z2 + • • •, for which R(1+zf“(z)/f‘(z))>−1/2 are investigated. The corrected version of a known results [2, Theorem 3.1 and Theorem 3.3] are also obtained.