TY - JOUR
T1 - Some Integral Mean Estimates for Polynomials with Restricted Zeros
AU - A. Mir, Q. M. Dawood & B. Dar
JO - Analysis in Theory and Applications
VL - 1
SP - 81
EP - 91
PY - 2017
DA - 2017/01
SN - 31
DO - http://doi.org/10.4208/ata.2015.v31.n1.7
UR - https://global-sci.org/intro/article_detail/ata/4624.html
KW - Polynomial, zeros, polar derivative.
AB - <p style="text-align: justify;">Let $P(z)$ be a polynomial of degree $n$ having all its zeros in $|z|\leq k$. For $k=1$, it is known that for each $r&gt; 0$ and $|\alpha|\geq 1$, $$n(|\alpha|-1)\Big\{\int_{0}^{2\pi}|P(e^{i\theta})|^{r}d\theta\Big\}^{\frac{1}{r}}\leq \Big\{\int_{0}^{2\pi}|1+e^{i\theta}|^{r}d\theta\Big\}^{\frac{1}{r}}\max_{|z|=1}\big|D_{\alpha}P(z)\big|.$$ In this paper, we shall first consider the case when $k\geq 1$ and present certain generalizations of this inequality. Also for $k\leq 1$, we shall prove an interesting result for Lacunary type of polynomials from which many results can be easily deduced.</p>