Abstract
For an entire function f(z), let\(M(f,r) = \mathop {\max |f(z)|}\limits_{|z| = r} \). If p(z) is a polynomial of degree n, then, in general, it is difficult to obtain a lower bound for M(p′, 1). But if the zeros of the polynomial are close to the origin, then various lower bounds for M(p′, 1) have been obtained in the past. In this paper, we have considered polynomials having all their zeros in ⋎z⋎≤k(k≥1), with a possible zero of order m(m≥0) at the origin and have obtained a lower bound for M(p′, 1), which is better than most of the known lower bounds. Our bound is sharp for m=0.
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Jain, V.K. On the derivative of a polynomial. Approx. Theory & its Appl. 13, 88–96 (1997). https://doi.org/10.1007/BF02836264
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DOI: https://doi.org/10.1007/BF02836264