JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Integration of Rational Function by Using Partial Fractions

  • question_answer
    \[\int_{{}}^{{}}{\frac{1}{\cos x(1+\cos x)}}\ dx=\]

    A)                 \[\log (\sec x+\tan x)+2\tan \frac{x}{2}+c\]

    B)                 \[\log (\sec x+\tan x)-2\tan \frac{x}{2}+c\]

    C)                 \[\log (\sec x+\tan x)+\tan \frac{x}{2}+c\]           

    D)                 \[\log (\sec x+\tan x)-\tan \frac{x}{2}+c\]

    Correct Answer: D

    Solution :

                       \[\int_{{}}^{{}}{\frac{1}{\cos x(1+\cos x)}}dx=\int_{{}}^{{}}{\frac{dx}{\cos x}-\int_{{}}^{{}}{\frac{dx}{1+\cos x}}}\]                                                       \[=\int_{{}}^{{}}{\sec x\ dx-\frac{1}{2}\int_{{}}^{{}}{{{\sec }^{2}}\frac{x}{2}dx}}\]                                                       \[=\log (\sec x+\tan x)-\tan \frac{x}{2}+c.\]


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