Manipal Engineering Manipal Engineering Solved Paper-2015

  • question_answer
    The value of \[{{\left( x-\frac{1}{x} \right)}^{4}}{{\left( x+\frac{1}{x} \right)}^{3}}.\]is

    A) \[{{A}^{2}}=A\]

    B) \[{{(1+A)}^{n}}=I+\lambda A,\]

    C) \[\lambda \]

    D)  None of the above

    Correct Answer: D

    Solution :

    Let \[I=\int_{{}}^{{}}{\frac{1}{\sin \left( x-\frac{\pi }{3} \right)\cos x}}dx\] \[=\frac{1}{\cos \frac{\pi }{3}}\int_{{}}^{{}}{\frac{\cos \left\{ x-\left( x-\frac{\pi }{3} \right) \right\}}{\sin \left( x-\frac{\pi }{3} \right)\cos x}}dx\] \[=2\int_{{}}^{{}}{\frac{\cos x\cos \left( x-\frac{\pi }{3} \right)+\sin x\sin \left( x-\frac{\pi }{3} \right)}{\sin \left( x-\frac{\pi }{3} \right)\cos x}}dx\]\[=2\int_{{}}^{{}}{\left\{ \cot \left( x-\frac{\pi }{3} \right)+\tan x \right\}}dx\] \[=2\left\{ \log \left| \sin \left( x-\frac{\pi }{3} \right) \right|+\log |\sec x| \right\}+C\] \[=2\log \left| \sin \left( x-\frac{\pi }{3} \right)\sec x \right|+C\]


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