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

  • question_answer
    The value of \[\int_{{}}^{{}}{\left( 1+\frac{1}{{{x}^{2}}} \right)\ {{e}^{\left( x-\frac{1}{x} \right)}}}\ dx\] equals    [Kurukshetra CEE 1998]

    A)            \[{{e}^{x-\frac{1}{x}}}+c\]

    B)            \[{{e}^{x+\frac{1}{x}}}+c\]

    C)            \[{{e}^{{{x}^{2}}-\frac{1}{x}}}+c\]

    D)            \[{{e}^{{{x}^{2}}+\frac{1}{{{x}^{2}}}}}+c\]

    Correct Answer: A

    Solution :

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


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