CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2011

  • question_answer
    If\[y={{({{\sin }^{-1}}x)}^{2}},\]then\[(1-{{x}^{2}})\frac{{{d}^{2}}y}{d{{x}^{2}}}-x\frac{dy}{dx}\]is equal to

    A)  \[0\]                                    

    B)  \[-1\]                   

    C)  \[-2\]                   

    D)         \[1\]

    E)  \[2\]

    Correct Answer: E

    Solution :

    \[y={{({{\sin }^{-1}}x)}^{2}}\] Differentiating on both sides, \[\frac{dy}{dx}=2{{\sin }^{-1}}x.\frac{1}{\sqrt{1-{{x}^{2}}}}\] \[\Rightarrow \]               \[\sqrt{1-{{x}^{2}}}=\frac{dy}{dx}=2{{\sin }^{-1}}x\] Differentiating on both sides, \[\sqrt{(1-{{x}^{2}})}\frac{{{d}^{2}}y}{d{{x}^{2}}}-\frac{2}{2\sqrt{1-{{x}^{2}}}}\frac{dy}{dx}=\frac{2}{\sqrt{1-{{x}^{2}}}}\] \[2(1-{{x}^{2}})\frac{{{d}^{2}}y}{d{{x}^{2}}}-2\frac{dy}{dx}.x=4\] \[\Rightarrow \]               \[(1-{{x}^{2}})\frac{{{d}^{2}}y}{d{{x}^{2}}}-x\frac{dy}{dx}=2\]


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