JCECE Engineering JCECE Engineering Solved Paper-2008

  • question_answer
    The value of\[\int_{2}^{3}{\frac{x+1}{{{x}^{2}}(x-1)}dx}\]is

    A) \[\log \frac{16}{9}+\frac{1}{6}\]                

    B) \[\log \frac{16}{9}-\frac{1}{6}\]

    C) \[2\log 2-\frac{1}{6}\]                   

    D) \[\log \frac{4}{3}-\frac{1}{6}\]

    Correct Answer: B

    Solution :

    Let          \[I=\int_{2}^{3}{\frac{x+1}{{{x}^{2}}(x-1)}dx}\]                    \[=\int_{2}^{3}{\left( \frac{-2}{x}-\frac{1}{{{x}^{2}}}+\frac{2}{x-1} \right)dx}\]                    \[=\left[ -2\log x+\frac{1}{x}+2\log (x-1) \right]_{2}^{3}\]                    \[=\left[ 2\log \left( \frac{x-1}{x} \right)+\frac{1}{x} \right]_{2}^{3}\]                    \[=\left[ 2\left( \log \frac{2}{3}-\log \frac{1}{2} \right)+\frac{1}{3}-\frac{1}{2} \right]\]                 \[=2\log \frac{4}{3}-\frac{1}{6}\]                 \[=\log \frac{16}{9}-\frac{1}{6}\]


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