BCECE Engineering BCECE Engineering Solved Paper-2011

  • question_answer
    \[\frac{d}{dx}\cos e{{c}^{-1}}\left( \frac{1+{{x}^{2}}}{2x} \right)\]is equal to

    A)  \[\frac{-2}{(1+{{x}^{2}})},x\ne 0\]    

    B)         \[\frac{2}{(1+{{x}^{2}})},x\ne 0\]     

    C)         \[\frac{2(1-{{x}^{2}})}{(1+{{x}^{2}})|1-{{x}^{2}}|},x\ne \pm 1,0\]

    D)         None of the above

    Correct Answer: C

    Solution :

     \[\frac{d}{dx}\cos e{{c}^{-1}}\left( \frac{1+{{x}^{2}}}{2x} \right)=\frac{d}{dx}{{\sin }^{-1}}\left( \frac{2x}{1+{{x}^{2}}} \right)\] \[=\frac{1}{\sqrt{1-{{\left( \frac{2x}{1+{{x}^{2}}} \right)}^{2}}}}\left( \frac{(1+{{x}^{2}})2-(2x)(2x)}{{{(1+{{x}^{2}})}^{2}}} \right)\] \[=\frac{2(1-{{x}^{2}})}{(1+{{x}^{2}})|1-{{x}^{2}}|},x\ne \pm 1,0\]


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