JCECE Engineering JCECE Engineering Solved Paper-2004

  • question_answer
    The value of\[I=\int_{0}^{1}{x\left| x-\frac{1}{2} \right|\,}dx\]is:

    A) \[\frac{1}{4}\]                                   

    B) \[\frac{1}{2}\]

    C) \[\frac{1}{8}\]                                   

    D)  none of these

    Correct Answer: C

    Solution :

    We have,                 \[I=\int_{0}^{1}{x}\left| x-\frac{1}{2} \right|\,\,dx\]                    \[=\int_{0}^{1/2}{x}\left( \frac{1}{2}-x \right)dx+\int_{1/2}^{1}{x}\left( x-\frac{1}{2} \right)\,dx\]                    \[=\int_{0}^{1/2}{\left( \frac{x}{2}-{{x}^{2}} \right)dx}+\int_{1/2}^{1}{\left( {{x}^{2}}-\frac{x}{2} \right)dx}\]                    \[=\left[ \frac{{{x}^{2}}}{4}-\frac{{{x}^{3}}}{3} \right]_{0}^{1/2}+\left[ \frac{1}{3}-\frac{1}{4}-\left( \frac{1}{24}-\frac{1}{16} \right) \right]\]                    \[=\frac{2}{16}-\frac{2}{24}+\frac{1}{12}\]                    \[=\frac{6-4+4}{48}=\frac{6}{48}\]                    \[=\frac{1}{8}\]


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