CEE Kerala Engineering CEE Kerala Engineering Solved Paper-2001

  • question_answer
    For \[y=\cos (m{{\sin }^{-1}}x)\]which of the following is true?

    A)  \[(1-{{x}^{2}}){{y}_{2}}+x{{y}_{1}}-{{m}^{2}}y=0\]

    B)  \[(1-{{x}^{2}}){{y}_{2}}-x{{y}_{1}}+{{m}^{2}}y=0\]

    C)  \[(1+{{x}^{2}}){{y}_{2}}+x{{y}_{1}}-{{m}^{2}}y=0\]

    D)  \[(1-{{x}^{2}}){{y}_{2}}+x{{y}_{1}}+{{m}^{2}}y=0\]

    E)  \[(1-x){{y}_{2}}-x{{y}_{1}}+{{m}^{2}}y=0\]

    Correct Answer: B

    Solution :

    \[y=\cos (m\,{{\sin }^{-1}}x)\] On differentiating w.r.t.\[x,\]we get \[{{y}_{1}}=-\sin (m{{\sin }^{-1}}x)\frac{m}{\sqrt{1-{{x}^{2}}}}\] \[\Rightarrow \]\[\sqrt{1-{{x}^{2}}}{{y}_{1}}=-m\sin (m{{\sin }^{-1}}x)\] \[\Rightarrow \]\[(1-{{x}^{2}}){{y}_{2}}-x{{y}_{1}}=-{{m}^{2}}y\] \[\Rightarrow \,\,\,\,(1-{{x}^{2}})\,{{y}_{2}}-x{{y}_{1}}+{{m}^{2}}y=0\]


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