On the Cauchy-Schwarz inequality
type: Item
instance of: scholarly article
title: On the Cauchy-Schwarz inequality
zbMATH Open document ID: 0933.26010
author: Horst Alzer
published in: Journal of Mathematical Analysis and Applications
publication date: 1999-12-21T00:00:00Z
review text: The author proves that the inequality \[ \left( \sum _{k=1}^{n}x_{k}\cdot y_{k}\right)^{2} \leq\sum _{k=1}^{n} y_{k} \cdot \sum _{k=1} ^{n} \left( \alpha + \frac{\beta}{k} \right) \cdot x_{k}^2 \cdot y_k \] holds for all positive sequences \((y_{k})_{k=1}^{n}\) and all positive starshaped sequences \((x_{k})_{k=1}^{n}\) (as where named in reviewer's paper [Math., Rev. Anal. Numér. Théor. Approximation, Anal. Numér. Théor. Approximation 12, 187-192 (1983; Zbl 0528.26005)] the sequences with the property \( 0 < x_{1} \leq x_{2}/2 \leq \cdots \leq x_{n} /n \)) if and only if \(\alpha \geq 3/4\) and \(\beta \geq 1- \alpha\). This result improves some inequalities given by \textit{Z. Liu} [J. Math. Anal. Appl. 218, No. 1, 13-21 (1998; Zbl 0891.26011)]and the author [J. Math. Anal. Appl. 168, No. 2, 596-604 (1992; Zbl 0763.26012)]. Reviewer's remark. Lemma 1, used in all these papers, was proven by the reviewer in the above mentioned paper.
Mathematics Subject Classification ID: 26D15
zbMATH DE Number: 1309042
zbMATH Keywords: Cauchy-Schwarz inequality
zbMATH Keywords: starshaped sequences
reviewed by: Gheorghe Toader
MaRDI profile type: Publication
full work available at URL: jmaa.1998.6252
OpenAlex ID: W2064956287
cites work: A refinement of the Cauchy-Schwarz inequality
cites work: Remark on refinement of the Cauchy-Schwarz inequality
cites work: Analytic Inequalities
DOI: 10.1006/JMAA.1998.6252
description: scientific article; zbMATH DE number 1309042