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  • P-ISSN3059-0604
  • E-ISSN3059-1309
  • KCI

MONOTONICITY AND LOGARITHMIC CONVEXITY OF THREE FUNCTIONS INVOLVING EXPONENTIAL FUNCTION

MONOTONICITY AND LOGARITHMIC CONVEXITY OF THREE FUNCTIONS INVOLVING EXPONENTIAL FUNCTION

한국수학교육학회지시리즈B:순수및응용수학 / Journal of the Korean Society of Mathematical Education Series B: Theoretical Mathematics and Pedagogical Mathematics, (P)3059-0604; (E)3059-1309
2008, v.15 no.4, pp.387-392
Guo, Bai-Ni (SCHOOL OF MATHEMATICS AND INFORMATICS, HENAN POLYTECHNIC UNIVERSITY)
Liu, Ai-Qi (DEPARTMENT OF MATHEMATICS, SANMENXIA POLYTECHNIC)
Qi, Feng (RESEARCH INSTITUTE OF MATHEMATICAL INEQUALITY THEORY, HENAN POLYTECHNIC UNIVERSITY)

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
alternative proof, monotonicity, logarithmic convexity, exponential function, extension, Hermite-Hadamard's integral inequality, inequality, power series expansion

한국수학교육학회지시리즈B:순수및응용수학