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

  • question_answer
    \[\int_{{}}^{{}}{{{e}^{x}}\sin x(\sin x+2\cos x)}\ dx=\]            [MP PET 1988]

    A)                 \[{{e}^{x}}{{\sin }^{2}}x+c\]

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

    C)                 \[{{e}^{x}}\sin 2x+c\]

    D)                 None of these

    Correct Answer: A

    Solution :

                    \[\int_{{}}^{{}}{{{e}^{x}}\sin x(\sin x+2\cos x)dx}\]                                 \[=\int_{{}}^{{}}{{{e}^{x}}{{\sin }^{2}}x\,dx}+\int_{{}}^{{}}{{{e}^{x}}2\sin x\,\cos xdx}\]                                 \[=\int_{{}}^{{}}{{{e}^{x}}{{\sin }^{2}}x\,dx}+\int_{{}}^{{}}{{{e}^{x}}\sin 2x\,dx}\]                            \[={{e}^{x}}{{\sin }^{2}}x-\int_{{}}^{{}}{{{e}^{x}}\sin 2x\,dx}+\int_{{}}^{{}}{{{e}^{x}}\sin 2x\,dx\,+c}\]                            \[={{e}^{x}}{{\sin }^{2}}x+c.\]                 Aliter : \[\int_{{}}^{{}}{{{e}^{x}}({{\sin }^{2}}x+\sin 2x)dx={{e}^{x}}{{\sin }^{2}}x+c.}\]


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