JEE Main & Advanced Mathematics Definite Integration Question Bank Summation of series by Definite Integration, Gamma function, Leibnitz's rule

  • question_answer
    Let \[f(x)=\int_{\,1}^{\,x}{\sqrt{2-{{t}^{2}}}dt}\]. Then real roots of the equation \[{{x}^{2}}-{f}'(x)=0\] are                                         [IIT Screening 2002]

    A)                 \[\pm 1\]            

    B)                 \[\pm \frac{1}{\sqrt{2}}\]

    C)                 \[\pm \,\,\frac{1}{2}\]  

    D)                 0 and 1

    Correct Answer: A

    Solution :

                       \[f'(x)=\sqrt{2-{{x}^{2}}}\]\[\Rightarrow {{x}^{2}}-\sqrt{2-{{x}^{2}}}=0\]            or  \[{{x}^{4}}+{{x}^{2}}-2=0\] or \[({{x}^{2}}+2)({{x}^{2}}-1)=0\]                                 \[\therefore {{x}^{2}}-1=0,\,\,\,\,\therefore x=\pm 1\].


You need to login to perform this action.
You will be redirected in 3 sec spinner