MONOTONICITY AND LOGARITHMIC CONVEXITY OF THREE FUNCTIONS INVOLVING EXPONENTIAL FUNCTION
Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics / Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics, (P)1226-0657; (E)2287-6081
2008, v.15 no.4, pp.387-392
Guo, Bai-Ni
Liu, Ai-Qi
Qi, Feng
Guo,,
B.
, Liu,,
A.
, &
Qi,,
F.
(2008). MONOTONICITY AND LOGARITHMIC CONVEXITY OF THREE FUNCTIONS INVOLVING EXPONENTIAL FUNCTION. Journal of the Korean Society of Mathematical Education Series B: The Pure and Applied Mathematics, 15(4), 387-392.
Abstract
In this note, an alternative proof and extensions are provided for the following conclusions in [6, Theorem 1 and Theorem 3]: The functions <TEX>$\frac1{x^2}-\frac{e^{-x}}{(1-e^{-x})^2}\;and\;\frac1{t}-\frac1{e^t-1}$</TEX> are decreasing in (0, <TEX>${\infty}$</TEX>) and the function <TEX>$\frac{t}{e^{at}-e^{(a-1)t}}$</TEX> for a <TEX>$a{\in}\mathbb{R}\;and\;t\;{\in}\;(0,\;{\infty})$</TEX> is logarithmically concave.
- keywords
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alternative proof,
monotonicity,
logarithmic convexity,
exponential function,
extension,
Hermite-Hadamard's integral inequality,
inequality,
power series expansion