English

The monotonicity results and sharp inequalities for some power-type means of two arguments

Classical Analysis and ODEs 2012-10-25 v1

Abstract

For a,b>0a,b>0 with aba\neq b, we define M_{p}=M^{1/p}(a^{p},b^{p})\text{if}p\neq 0 \text{and} M_{0}=\sqrt{ab}, where M=A,He,L,I,P,T,N,ZM=A,He,L,I,P,T,N,Z and YY stand for the arithmetic mean, Heronian mean, logarithmic mean, identric (exponential) mean, the first Seiffert mean, the second Seiffert mean, Neuman-S\'{a}ndor mean, power-exponential mean and exponential-geometric mean, respectively. Generally, if MM is a mean of aa and bb, then MpM_{p} is also, and call "power-type mean". We prove the power-type means PpP_{p}, TpT_{p}, NpN_{p}, ZpZ_{p} are increasing in pp on R\mathbb{R} and establish sharp inequalities among power-type means ApA_{p}, HepHe_{p}, LpL_{p}, IpI_{p}, PpP_{p}, NpN_{p}, ZpZ_{p}, YpY_{p}% . From this a very nice chain of inequalities for these means L_{2}<P<N_{1/2}<He<A_{2/3}<I<Z_{1/3}<Y_{1/2} follows. Lastly, a conjecture is proposed.

Keywords

Cite

@article{arxiv.1210.6478,
  title  = {The monotonicity results and sharp inequalities for some power-type means of two arguments},
  author = {Zhen-Hang Yang},
  journal= {arXiv preprint arXiv:1210.6478},
  year   = {2012}
}

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11 pages