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

  • question_answer
    \[\int_{{}}^{{}}{\frac{{{e}^{x}}(x+1)}{{{\cos }^{2}}(x{{e}^{x}})}dx=}\] [Roorkee 1979; MP PET 1995; Pb. CET 2001]

    A)            \[\tan (x{{e}^{x}})+c\]

    B)            \[\sec (x{{e}^{x}})\tan (x{{e}^{x}})+c\]

    C)            \[-\tan (x{{e}^{x}})+c\]

    D)            None of these

    Correct Answer: A

    Solution :

                       \[\int_{{}}^{{}}{\frac{{{e}^{x}}(x+1)}{{{\cos }^{2}}(x{{e}^{x}})}=\int_{{}}^{{}}{{{e}^{x}}(x+1){{\sec }^{2}}(x{{e}^{x}})dx}}\]            Putting \[x{{e}^{x}}=t\Rightarrow (x+1){{e}^{x}}dx=dt\], we get            \[\int_{{}}^{{}}{{{\sec }^{2}}t\,dt=\tan t+c}=\tan (x{{e}^{x}})+c.\]


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