Inequalities for the S th Derivative of Polynomials Not Vanishing inside A Circle

Abstract

Let P(z) be a polynomial of degree n having all its zeros in , then for , Bidkham and Dewan [J. Math. Anal. Appl. 166(1992), 191-193] proved max In this paper, we prove an interesting generalization as well as an improvement of this result by considering the s th derivative of lacunary type of polynomials P(z) of degree n > 3.