VIT Engineering VIT Engineering Solved Paper-2009

  • question_answer
    If \[{{I}_{n}}=\int{{{\sin }^{n}}x\,dx},\] then \[n{{I}_{n}}-(n-1)\,{{l}_{n-2}}\]equals

    A)  \[{{\sin }^{n-1}}x\,\cos x\]

    B)  \[{{\cos }^{n-1}}x\,\,\sin x\]

    C)  \[-{{\sin }^{n-1}}x\,\,\cos x\]

    D)  \[-{{\cos }^{n-1}}x\,\,\sin x\]

    Correct Answer: C

    Solution :

    We know that, if \[{{I}_{n}}=\int{{{\sin }^{n}}x\,dx,\,\text{then}}\] \[{{I}_{n}}=-\frac{{{\sin }^{n-1}}x\,\cos x}{n}+\frac{n-1}{n}{{I}_{n-2}}\] where n is a positive integer. \[\Rightarrow \]\[n{{I}_{n}}-(n-1){{I}_{n-2}}=-{{\sin }^{n-1}}x\cos x\]


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