摘要
We introduce notations E(r)={z:|z|>r},E=E(1), and suppose It is considered in [2] that F(z) is a starlike function in E (2^(1/2)), if The purpose of this paper is to give adifferent proof of this theorem, and extend this theorem as follows: Suppose Let ∑(λ) denote the class of all functions (1) satisfying the condition where d_n(λ) is the coeffients of the development Then the starlike radius r_0 of the class ∑(λ) is the unique solution of the algebric equation λr^(2(k+1))-2λr^(2(k+1))+λr^(2k)-(k+1-λ)r^2+k-λ=0 in (1,∞).
