An Optimal Double Inequality between Power-Type Heron and Seiffert Means

作者:Chu, Yu-Ming*; Wang, Miao-Kun; Qiu, Ye-Fang
来源:JOURNAL OF INEQUALITIES AND APPLICATIONS, 2010, 146945.
DOI:10.1155/2010/146945

摘要

For k is an element of [0, +infinity), the power-type Heron mean H-k(a,b) and the Seiffert mean T(a,b) of two positive real numbers a and b are defined by H-k(a,b) = ((a(k) + (ab()k/2) + b(k))/3)(1/k), k not equal 0; H-k(a,b) =root ab, k = 0 and T(a,b) = (a - b)/2arctan((a - b)/(a + b)), a not equal b; T(a,b) = a, a = b, respectively. In this paper, we find the greatest value p and the least value q such that the double inequality H-p(a,b) < T(a,b) < H-q(a,b) holds for all a, b > 0 with a not equal b.