JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Integration by Substitution

  • question_answer
    \[\int_{{}}^{{}}{\frac{1}{x}\log x\ dx}\] is equal to [SCRA 1996]

    A)            \[\frac{1}{2}\log x+c\]

    B)            \[\frac{1}{2}{{(\log x)}^{2}}+c\]

    C)            \[\frac{1}{2}\log {{(x)}^{2}}+c\]

    D)            \[\log x+c\]

    Correct Answer: B

    Solution :

               \[I=\int_{{}}^{{}}{\frac{1}{x}\log x\,dx}\]. Put \[\log x=t\Rightarrow \frac{1}{x}\,dx=dt\]            \[\therefore \,\,\,I\int_{{}}^{{}}{t\,dt}=\frac{{{t}^{2}}}{2}+c=\frac{{{(\log x)}^{2}}}{2}+c\].


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