Note on Certain Inequalities for Means in Two Variables

Given the positive real numbers x and y, let A(x, y), G(x, y), and I(x, y) denote their arithmetic mean, geometric mean, and identric mean, respectively. It is proved that for p ≥ 2, the double inequality αA(x, y) + (1− α)G(x, y) < I(x, y) < βA(x, y) + (1− β)G(x, y) holds true for all positive real numbers x 6= y if and only if α ≤ ( 2 e )p and β ≥ 23 . This result complements a similar one established by H. Alzer and S.-L. Qiu [Inequalities for means in two variables, Arch. Math. (Basel) 80 (2003), 201–215].