JEE Main & Advanced Mathematics Indefinite Integrals Question Bank Self Evaluation Test - Integrals

  • question_answer
    What is \[\int{{{\tan }^{2}}x{{\sec }^{4}}x\,dx}\] equal to?

    A) \[\frac{{{\sec }^{5}}x}{5}+\frac{{{\sec }^{3}}x}{3}+c\]

    B) \[\frac{{{\tan }^{5}}x}{5}+\frac{{{\tan }^{3}}x}{3}+c\]

    C) \[\frac{{{\tan }^{5}}x}{5}+\frac{{{\sec }^{3}}x}{3}+c\]

    D) \[\frac{{{\sec }^{5}}x}{5}+\frac{{{\tan }^{3}}x}{3}+c\]

    Correct Answer: B

    Solution :

    [b] Let \[I=\int{{{\tan }^{2}}x{{\sec }^{4}}xdx}\] Let \[\tan x=t\] \[\Rightarrow {{\sec }^{2}}xdx=dt\] \[\therefore I=\int{{{\tan }^{2}}x.{{\sec }^{2}}x.{{\sec }^{2}}x.dx}\] \[=\int{{{\tan }^{2}}x(1+{{\tan }^{2}}x){{\sec }^{2}}x.dx}\] \[\therefore I=\int{{{t}^{2}}(1+{{t}^{2}})dt=\int{({{t}^{2}}+{{t}^{4}})dt}}\] \[=\frac{{{t}^{5}}}{5}+\frac{{{t}^{3}}}{3}+c=\frac{{{\tan }^{5}}x}{5}+\frac{{{\tan }^{3}}x}{3}+c\]


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