JEE Main & Advanced Sample Paper JEE Main Sample Paper-22

  • question_answer
    If the range of the function\[f(x)=\sqrt{1+{{\tan }^{-1}}x}+\sqrt{1-{{\tan }^{-1}}x}\] is [a, b] then the value of \[({{a}^{2}}+{{b}^{2}})\]

    A)  3                                

    B)  4

    C)  5                                

    D)  6

    Correct Answer: D

    Solution :

    For y to the real \[-1\le {{\tan }^{-1}}\,x\le 1\] \[\begin{align}   & \Rightarrow \,\,-\tan \,1\le x\le \tan 1 \\  & \,\,\,\,\,\,\,\,y=\sqrt{\operatorname{t}+1}\,\,+\sqrt{1-t} \\ \end{align}\] \[\Rightarrow \,\,{{y}^{2}}=2+2\sqrt{1-{{t}^{2}}}\] \[\Rightarrow \,\,\,{{y}^{2}}\,\in \,[2,4]\] \[\Rightarrow \,\,\,y\in \left[ \sqrt{2},\,\,2 \right]\] \[\Rightarrow \,\,({{a}^{2}}+{{b}^{2}})=6\]


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