CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2010

  • question_answer
    If  \[\int{\frac{\sqrt{x}}{x(x+1)}}\,dx=k\,{{\tan }^{-1}}m,\]then \[(k,m)\] is

    A) \[(2,x)\]                              

    B) \[(1,x)\]

    C) \[(1,\sqrt{x})\]                 

    D) \[(2,\sqrt{x})\]

    Correct Answer: D

    Solution :

     \[\int{\frac{\sqrt{x}}{x(x+1)}}dx=k{{\tan }^{-1}}m\] Put         \[\left\{ \begin{matrix}    x={{\tan }^{2}}\theta   \\    dx=2\tan \theta .{{\sec }^{2}}\theta d\theta   \\ \end{matrix} \right.\]                 \[=\int{\frac{\tan \theta }{{{\tan }^{2}}\theta .{{\sec }^{2}}\theta }.(2tan\theta .se{{c}^{2}})}d\theta \]                 \[=2\int{d\theta .=2\theta =2{{\tan }^{-1}}\sqrt{x}}=k{{\tan }^{-1}}(m)\] On comparing, we get \[(k,m)=(2,\sqrt{x})\]


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