J & K CET Engineering J and K - CET Engineering Solved Paper-2008

  • question_answer
    \[\int{\sin \,\,\sqrt{x}}\,\,dx\] is equal to

    A)  \[\sin \sqrt{x}-\sqrt{x}\,\cos \,\sqrt{x}\]

    B)  \[2(\sin \,\sqrt{x}-\sqrt{x}\,\cos \,\sqrt{x})+c\]

    C)  \[\cos \,\sqrt{x}-\sqrt{x}\,\sin \,\sqrt{x}+c\]

    D)  \[2(\cos \sqrt{x}-\sqrt{x}\,\sin \sqrt{x})+c\]

    Correct Answer: B

    Solution :

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


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