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

  • question_answer
    \[\int_{{}}^{{}}{\frac{\sqrt{x}}{1+x}dx=}\]

    A)            \[\sqrt{x}-{{\tan }^{-1}}\sqrt{x}+c\]

    B)            \[2(\sqrt{x}-{{\tan }^{-1}}\sqrt{x})+c\]

    C)            \[2(\sqrt{x}+{{\tan }^{-1}}x)+c\]

    D)            \[\sqrt{1+x}+c\]

    Correct Answer: B

    Solution :

                       \[\int_{{}}^{{}}{\frac{\sqrt{x}}{1+x}\,dx=\int_{{}}^{{}}{\frac{\sqrt{x}\sqrt{x}}{\sqrt{x}(1+x)}\,dx}}\]            \[=\int_{{}}^{{}}{\frac{x+1}{\sqrt{x}(x+1)}\,dx-\int_{{}}^{{}}{\frac{1}{\sqrt{x}(x+1)}\,dx}}\]            \[=\int_{{}}^{{}}{\frac{1}{\sqrt{x}}\,dx-\int_{{}}^{{}}{\frac{1}{\sqrt{x}(x+1)}\,dx}}\]            \[=2{{x}^{1/2}}-2{{\tan }^{-1}}\sqrt{x}+c=2(\sqrt{x}-{{\tan }^{-1}}\sqrt{x})+c.\]


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