JEE Main & Advanced Mathematics Functions Question Bank Functions

  • question_answer
    The domain of the function \[f(x)=\frac{{{\sin }^{-1}}(3-x)}{\ln (|x|\ -2)}\] is [Orissa JEE 2002]

    A)            [2, 4]

    B)            (2, 3) È (3, 4]

    C)            [2,\[\infty \])

    D)            \[(-\infty ,\ -3)\cup [2,\ \infty )\]

    Correct Answer: B

    Solution :

               \[f(x)=\frac{{{\sin }^{-1}}(3-x)}{\log \left[ |x|-2 \right]}\]            Let \[g(x)={{\sin }^{-1}}(3-x)\] Þ \[-1\le 3-x\le 1\]            Domain of \[g(x)\] is [2, 4]            and let \[h(x)=\log \left[ |x|-2 \right]\] Þ \[|x|-2>0\]            Þ \[|x|\,>2\]  Þ \[x<-2\] or \[x>2\]  Þ \[(-\infty ,\,-2)\cup (2,\,\infty )\]            we know that            \[(f/g)(x)=\]\[\frac{f(x)}{g(x)}\forall x\in {{D}_{1}}\cap {{D}_{2}}-\left\{ x\in R:g(x)=0 \right\}\] \ Domain of \[f(x)=(2,\,4]-\{3\}\]\[=(2,\,3)\cup (3,\,4]\].


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