JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Mock Test - Integrals

  • question_answer
    If \[{{I}_{n}}=\int {{(ln\,x)}^{n}}dx\], then \[{{I}_{n}}+n{{I}_{n-1}}\]=

    A) \[\frac{{{(ln\,x)}^{n}}}{x}+C\]

    B) \[x{{(ln\,x)}^{n-1}}+C\]

    C) \[x{{(ln\,x)}^{n}}+C\] 

    D) none of these

    Correct Answer: C

    Solution :

    [c] \[{{I}_{n}}=x{{(\ln x)}^{n}}-\int{\frac{x(n){{(\ln x)}^{n-1}}}{x}}dx\] \[={{(\ln x)}^{n}}-n\,{{I}_{(n-1)}}\] or \[{{I}_{n}}+n{{I}_{n-1}}=x{{(\ln x)}^{n}}\]


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