On a generalization of an upper bound for the exponential function (Q1014652)

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scientific article; zbMATH DE number 5549398
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On a generalization of an upper bound for the exponential function
scientific article; zbMATH DE number 5549398

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    On a generalization of an upper bound for the exponential function (English)
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    29 April 2009
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    In this paper, a generalization of an upper bound for the exponential function is obtained. Let \[ U(n,x)=1-\frac{1}{n}+\frac{1}{n}(\frac{1+(1-\frac{1}{n})x}{1-\frac{x}{n}})^{n}, \] and \[ \frac{1}{n-1}(U(n,x)-(1-x)^{-1})=\sum_{k=2}^{\infty}\frac{P_{k}(n)x^{k}}{k!n^{k-1}}. \] The new results are obtained: (1) \(\exp(\frac{n(x-1)}{n+x-1})\leq\frac{n-1+x^{n}}{n}\), for \(n=p/q, p>2q>0, x>-1\), or \(p<2q, x>(1-p/q)^{1/q}\) (\(p,q\) are odd integers); (2) \(P_{k}(n)\) is a monic polynomial of degree \(2k-3\).
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    upper bound
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    exponential function
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    polynomials
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