<p>Let <i>P</i>(<i>z</i>) be a polynomial of degree <i>n</i> having all its zeros in <InlineEquation ID="IEq1"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_IEq1.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="111" /> </InlineMediaObject> <EquationSource Format="TEX">\(|z|\le k,~k\ge 1,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mo stretchy="false">|</mo> <mi>z</mi> <mo stretchy="false">|</mo> <mo>≤</mo> <mi>k</mi> <mo>,</mo> <mspace width="3.33333pt" /> <mi>k</mi> <mo>≥</mo> <mn>1</mn> <mo>,</mo> </mrow> </math></EquationSource> </InlineEquation> it is known for every non-zero vector <InlineEquation ID="IEq2"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_IEq2.gif" Format="GIF" Height="20" Rendition="HTML" Resolution="72" Type="Linedraw" Width="287" /> </InlineMediaObject> <EquationSource Format="TEX">\(\gamma =(\gamma _1,\gamma _2,\ldots ,\gamma _n), ~\gamma _j\ge 0, ~1\le j\le n,\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>γ</mi> <mo>=</mo> <mrow> <mo stretchy="false">(</mo> <msub> <mi>γ</mi> <mn>1</mn> </msub> <mo>,</mo> <msub> <mi>γ</mi> <mn>2</mn> </msub> <mo>,</mo> <mo>…</mo> <mo>,</mo> <msub> <mi>γ</mi> <mi>n</mi> </msub> <mo stretchy="false">)</mo> </mrow> <mo>,</mo> <mspace width="3.33333pt" /> <msub> <mi>γ</mi> <mi>j</mi> </msub> <mo>≥</mo> <mn>0</mn> <mo>,</mo> <mspace width="3.33333pt" /> <mn>1</mn> <mo>≤</mo> <mi>j</mi> <mo>≤</mo> <mi>n</mi> <mo>,</mo> </mrow> </math></EquationSource> </InlineEquation> that <Equation ID="Equ1"> <EquationNumber>1</EquationNumber> <MediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_Equ1.gif" Format="GIF" Height="41" Rendition="HTML" Resolution="72" Type="Linedraw" Width="317" /> </MediaObject> <EquationSource Format="TEX">\(\begin{aligned} \max _{|z|=1}|D_\alpha ^\gamma P(z)|\ge \frac{|\gamma |}{1+k^n}(|\alpha |-k)\max _{|z|=1}|P(z)|, \end{aligned}\)</EquationSource> <EquationSource Format="MATHML"><math display="block"> <mrow> <mtable> <mtr> <mtd columnalign="right"> <mrow> <munder> <mo movablelimits="true">max</mo> <mrow> <mo stretchy="false">|</mo> <mi>z</mi> <mo stretchy="false">|</mo> <mo>=</mo> <mn>1</mn> </mrow> </munder> <mrow> <mo stretchy="false">|</mo> </mrow> <msubsup> <mi>D</mi> <mi>α</mi> <mi>γ</mi> </msubsup> <mrow> <mi>P</mi> <mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">|</mo> <mo>≥</mo> </mrow> <mfrac> <mrow> <mo stretchy="false">|</mo> <mi>γ</mi> <mo stretchy="false">|</mo> </mrow> <mrow> <mn>1</mn> <mo>+</mo> <msup> <mi>k</mi> <mi>n</mi> </msup> </mrow> </mfrac> <mrow> <mo stretchy="false">(</mo> <mo stretchy="false">|</mo> <mi>α</mi> <mo stretchy="false">|</mo> <mo>-</mo> <mi>k</mi> <mo stretchy="false">)</mo> </mrow> <munder> <mo movablelimits="true">max</mo> <mrow> <mo stretchy="false">|</mo> <mi>z</mi> <mo stretchy="false">|</mo> <mo>=</mo> <mn>1</mn> </mrow> </munder> <mrow> <mo stretchy="false">|</mo> <mi>P</mi> <mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> <mo stretchy="false">|</mo> </mrow> <mo>,</mo> </mrow> </mtd> </mtr> </mtable> </mrow> </math></EquationSource> </Equation>where <InlineEquation ID="IEq3"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_IEq3.gif" Format="GIF" Height="19" Rendition="HTML" Resolution="72" Type="Linedraw" Width="58" /> </InlineMediaObject> <EquationSource Format="TEX">\(D_\alpha ^\gamma P(z)\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <msubsup> <mi>D</mi> <mi>α</mi> <mi>γ</mi> </msubsup> <mi>P</mi> <mrow> <mo stretchy="false">(</mo> <mi>z</mi> <mo stretchy="false">)</mo> </mrow> </mrow> </math></EquationSource> </InlineEquation> is the generalized polar derivative of <i>P</i>(<i>z</i>) with respect to a real or complex number <InlineEquation ID="IEq4"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_IEq4.gif" Format="GIF" Height="10" Rendition="HTML" Resolution="72" Type="Linedraw" Width="14" /> </InlineMediaObject> <EquationSource Format="TEX">\(\alpha \)</EquationSource> <EquationSource Format="MATHML"><math> <mi>α</mi> </math></EquationSource> </InlineEquation> and <InlineEquation ID="IEq5"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_IEq5.gif" Format="GIF" Height="23" Rendition="HTML" Resolution="72" Type="Linedraw" Width="101" /> </InlineMediaObject> <EquationSource Format="TEX">\(|\gamma |=\sum _{j=1}^{n}\gamma _j\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mrow> <mo stretchy="false">|</mo> <mi>γ</mi> <mo stretchy="false">|</mo> </mrow> <mo>=</mo> <msubsup> <mo>∑</mo> <mrow> <mi>j</mi> <mo>=</mo> <mn>1</mn> </mrow> <mi>n</mi> </msubsup> <msub> <mi>γ</mi> <mi>j</mi> </msub> </mrow> </math></EquationSource> </InlineEquation>. In this paper, we shall present the <InlineEquation ID="IEq6"> <InlineMediaObject> <ImageObject Color="BlackWhite" FileRef="13226_2025_855_Article_IEq6.gif" Format="GIF" Height="15" Rendition="HTML" Resolution="72" Type="Linedraw" Width="27" /> </InlineMediaObject> <EquationSource Format="TEX">\(q-\)</EquationSource> <EquationSource Format="MATHML"><math> <mrow> <mi>q</mi> <mo>-</mo> </mrow> </math></EquationSource> </InlineEquation>integral mean extension of (<InternalRef RefID="Equ1">1</InternalRef>). The results obtained not only provide a parallel analogue of inequalities for the polar derivative of a polynomial but also yield other interesting inequalities as special cases.</p>

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Integral mean extension of Turán type inequalities involving generalized polar derivative of a polynomial

  • F. A. Bhat,
  • H. A. Dar,
  • H. A. Laway

摘要

Let P(z) be a polynomial of degree n having all its zeros in \(|z|\le k,~k\ge 1,\) | z | k , k 1 , it is known for every non-zero vector \(\gamma =(\gamma _1,\gamma _2,\ldots ,\gamma _n), ~\gamma _j\ge 0, ~1\le j\le n,\) γ = ( γ 1 , γ 2 , , γ n ) , γ j 0 , 1 j n , that 1 \(\begin{aligned} \max _{|z|=1}|D_\alpha ^\gamma P(z)|\ge \frac{|\gamma |}{1+k^n}(|\alpha |-k)\max _{|z|=1}|P(z)|, \end{aligned}\) max | z | = 1 | D α γ P ( z ) | | γ | 1 + k n ( | α | - k ) max | z | = 1 | P ( z ) | , where \(D_\alpha ^\gamma P(z)\) D α γ P ( z ) is the generalized polar derivative of P(z) with respect to a real or complex number \(\alpha \) α and \(|\gamma |=\sum _{j=1}^{n}\gamma _j\) | γ | = j = 1 n γ j . In this paper, we shall present the \(q-\) q - integral mean extension of (1). The results obtained not only provide a parallel analogue of inequalities for the polar derivative of a polynomial but also yield other interesting inequalities as special cases.