Manipal Engineering Manipal Engineering Solved Paper-2008

  • question_answer
    \[\frac{d}{dx}{{\sin }^{-1}}(x\sqrt{1-x}+\sqrt{x}\sqrt{1-{{x}^{2}}})\]

    A) \[-\frac{1}{2x\sqrt{1-x}}-\frac{1}{\sqrt{1-{{x}^{2}}}}\]

    B) \[\frac{1}{2\sqrt{x}\sqrt{1-x}}-\frac{1}{\sqrt{1-{{x}^{2}}}}\]

    C) \[\frac{1}{2\sqrt{x}\sqrt{1-x}}+\frac{1}{\sqrt{1-{{x}^{2}}}}\]

    D) \[-\frac{1}{2\sqrt{x}\sqrt{1-x}}+\frac{1}{\sqrt{1-{{x}^{2}}}}\]

    Correct Answer: C

    Solution :

                    \[\frac{d}{dx}\{{{\sin }^{-1}}(x\sqrt{1-x}+\sqrt{x}\sqrt{1-{{x}^{2}}})\}\] \[=\frac{d}{dx}{{\sin }^{-1}}\{(x\sqrt{1-{{(\sqrt{x})}^{2}}}+\sqrt{x}\sqrt{1-{{x}^{2}}})\}\]                 \[\left[ \begin{align}   & \because \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,{{\sin }^{-1}}A+{{\sin }^{-1}}B \\  & ={{\sin }^{-1}}(A\sqrt{1-{{B}^{2}}}+B\sqrt{1-{{A}^{2}}}) \\ \end{align} \right]\] \[\Rightarrow \]               \[\frac{d}{dx}\{{{\sin }^{-1}}(x\sqrt{1-{{(\sqrt{x})}^{2}}}+\sqrt{x}\sqrt{1-{{x}^{2}}})\}\]                 \[=\frac{d}{dx}({{\sin }^{-1}}x+{{\sin }^{-1}}\sqrt{x})\]                 \[=\frac{1}{\sqrt{1-{{x}^{2}}}}+\frac{1}{2\sqrt{x}\sqrt{1-x}}\]


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