Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means

We prove that αH(a,b)+(1−α)L(a,b)>M(1−4α)/3(a,b) for α∈(0,1) and all a,b>0 with a≠b if and only if α∈[1/4,1) and αH(a,b)+(1−α)L(a,b)<M(1−4α)/3(a,b) if and only if α∈(0,3345/80−11/16), and the parameter (1−4α)/3 is the best possible in either case. Here, H(a,b)=2ab/(a+b), L(a,b)=(a−b)/(log ...

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Main Authors: Wei-Mao Qian, Zhong-Hua Shen
Format: Article
Language:English
Published: Wiley 2012-01-01
Series:Journal of Applied Mathematics
Online Access:http://dx.doi.org/10.1155/2012/471096
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author Wei-Mao Qian
Zhong-Hua Shen
author_facet Wei-Mao Qian
Zhong-Hua Shen
author_sort Wei-Mao Qian
collection DOAJ
description We prove that αH(a,b)+(1−α)L(a,b)>M(1−4α)/3(a,b) for α∈(0,1) and all a,b>0 with a≠b if and only if α∈[1/4,1) and αH(a,b)+(1−α)L(a,b)<M(1−4α)/3(a,b) if and only if α∈(0,3345/80−11/16), and the parameter (1−4α)/3 is the best possible in either case. Here, H(a,b)=2ab/(a+b), L(a,b)=(a−b)/(log a−log b), and Mp(a,b)=((ap+bp)/2)1/p (p≠0) and M0(a,b)=ab are the harmonic, logarithmic, and pth power means of a and b, respectively.
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spelling doaj-art-4cdd6d18126f42d79fcb40c4ae1582f62025-02-03T05:47:35ZengWileyJournal of Applied Mathematics1110-757X1687-00422012-01-01201210.1155/2012/471096471096Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic MeansWei-Mao Qian0Zhong-Hua Shen1School of Distance Education, Huzhou Broadcast and TV University, Huzhou 313000, ChinaDepartment of Mathematics, Hangzhou Normal University, Hangzhou 310036, ChinaWe prove that αH(a,b)+(1−α)L(a,b)>M(1−4α)/3(a,b) for α∈(0,1) and all a,b>0 with a≠b if and only if α∈[1/4,1) and αH(a,b)+(1−α)L(a,b)<M(1−4α)/3(a,b) if and only if α∈(0,3345/80−11/16), and the parameter (1−4α)/3 is the best possible in either case. Here, H(a,b)=2ab/(a+b), L(a,b)=(a−b)/(log a−log b), and Mp(a,b)=((ap+bp)/2)1/p (p≠0) and M0(a,b)=ab are the harmonic, logarithmic, and pth power means of a and b, respectively.http://dx.doi.org/10.1155/2012/471096
spellingShingle Wei-Mao Qian
Zhong-Hua Shen
Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means
Journal of Applied Mathematics
title Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means
title_full Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means
title_fullStr Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means
title_full_unstemmed Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means
title_short Inequalities between Power Means and Convex Combinations of the Harmonic and Logarithmic Means
title_sort inequalities between power means and convex combinations of the harmonic and logarithmic means
url http://dx.doi.org/10.1155/2012/471096
work_keys_str_mv AT weimaoqian inequalitiesbetweenpowermeansandconvexcombinationsoftheharmonicandlogarithmicmeans
AT zhonghuashen inequalitiesbetweenpowermeansandconvexcombinationsoftheharmonicandlogarithmicmeans