JEE Main & Advanced Mathematics Functions Question Bank Functions

  • question_answer
    The natural domain of the real valued function defined by \[f(x)=\sqrt{{{x}^{2}}-1}+\sqrt{{{x}^{2}}+1}\] is                        [SCRA 1996]

    A)                    \[1<x<\infty \]

    B)             \[-\infty <x<\infty \]

    C)            \[-\infty <x<-1\]

    D)            \[(-\infty ,\ \infty )-(-1,\ 1)\]

    Correct Answer: D

    Solution :

               \[f(x)=\sqrt{{{x}^{2}}-1}+\sqrt{{{x}^{2}}+1}\,\,\Rightarrow \,\,f(x)={{y}_{1}}+{{y}_{2}}\]            Domain of \[{{y}_{1}}=\sqrt{{{x}^{2}}-1}\,\Rightarrow \,\,{{x}^{2}}-1\ge 0\,\,\Rightarrow \,\,{{x}^{2}}\ge 1\]            \[x\in (-\,\infty ,\,\,\infty )-(-1,\,\,1)\] and Domain of \[{{y}_{2}}\] is real number,  \[\therefore \] Domain of \[f(x)=(-\infty ,\,\,\infty )-(-1,\,\,1)\].


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