Some Results Concerned with Hankel Determinant

Abstract

In this paper, we discuss different versions of the boundary Schwarz lemma and Hankel determinant for K (α) class. Also, for the function, we estimate a modulus of the angular derivative of f (z) function at the boundary point z 0 with f (z 0 ) = z0 1+α and f ′ (z 0 ) = 1 1+α . That is, we shall give an estimate below |f ′′ (z 0 )| according to the first nonzero Taylor coefficient of about two zeros, namely z = 0 and z 1 ̸ = 0. The sharpness of this inequality is also proved.