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

  • question_answer
    What is \[\int\limits_{-\frac{\pi }{6}}^{\frac{\pi }{6}}{\frac{{{\sin }^{5}}x{{\cos }^{3}}x}{{{x}^{4}}}}dx\] equal to?

    A) \[\frac{\pi }{2}\]

    B) \[\frac{\pi }{4}\]

    C) \[\frac{\pi }{8}\]

    D) 0

    Correct Answer: D

    Solution :

    [d] Let \[f(x)=\frac{{{\sin }^{5}}x{{\cos }^{3}}x}{{{x}^{4}}}\] \[f(-x)=\frac{{{\sin }^{5}}(-x){{\cos }^{3}}(-x)}{{{(-x)}^{4}}}\] \[=\frac{-{{\sin }^{5}}x{{\cos }^{3}}x}{{{x}^{4}}}=-f(x)\] \[\Rightarrow f(x)\] is an odd function. Hence, \[\int\limits_{-\frac{\pi }{6}}^{\frac{\pi }{6}}{\frac{{{\sin }^{5}}x{{\cos }^{3}}x}{{{x}^{4}}}dx=0}\]


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