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Today's calculation of Integral 310

Source: 2008 Kyusyu University entrance exam/Engineering, 2nd Round

March 13, 2008
calculusintegrationfunctionlogarithmscalculus computations

Problem Statement

Define the function f(x) f(x) as : \displaystyle f(x)\equal{}\left\{ \begin{array}{ll} \frac{\ln (1\plus{}x)}{1\plus{}x}\ (x\geq 0) &  \\ \frac{\ln (1\minus{}x)}{1\minus{}x}\ (\minus{}1\leq x<0) &  \end{array} \right. 1. Examine the variation of f(x) f(x) and find the maximum and minimum value of f(x) f(x). 2. Find the value of a a for which \int_{\minus{}1}^{e\minus{}1} |f(x)\minus{}a|\ dx is minimized for 0a1e 0\leq a\leq \frac{1}{e}.