On the Fekete-Szegö problem

摘要

Let f(z)=z+a2z2+a3z3+⋯ be an analytic function in the open unit disk. A sharp upper bound is obtained for |a3−μa22| by using the class of strongly starlike functions of order β and type α when 0⩽λ⩽1 and μ⩾1.