RAJASTHAN ­ PET Rajasthan PET Solved Paper-2001

  • question_answer
    \[\frac{\cos \sqrt{x}}{\sqrt{x}}\]is equal to

    A)  \[\sin \sqrt{x}+c\]      

    B)  \[2\sin \sqrt{x}+c\]

    C)  \[-\sin \sqrt{x}+c\]      

    D)  \[-2\sin \sqrt{x}+c\]

    Correct Answer: B

    Solution :

     Let \[I=\int{\frac{\cos \sqrt{x}}{\sqrt{x}}}dx\] Let \[\sqrt{x}=t\] \[\Rightarrow \] \[\frac{1}{2\sqrt{x}}dx=dt\] \[\Rightarrow \] \[\frac{1}{\sqrt{x}}dx=2dt\] \[\therefore \] \[I=\int{\cos t2.dt}\] \[=2\sin t+c\] \[=2\sin \sqrt{x}+c\]


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