JEE Main & Advanced Mathematics Functions Question Bank Continuity

  • question_answer
    For the function \[f(x)=\left\{ \begin{align}   & \frac{{{\sin }^{2}}ax}{{{x}^{2}}},\,\text{when}\,x\ne 0 \\  & \,\,\,\,\,\,\,\,\,\,\,\,\,\,1,\text{when}\,x=0 \\ \end{align} \right.\] which one is a true statement                              

    A)            \[f(x)\]is continuous at \[x=0\]

    B)            \[f(x)\]is discontinuous at \[x=0\], when \[a\ne \pm 1\]

    C)            \[\underset{x\to 1}{\mathop{\lim }}\,(1-x+[x-1]+[1-x])\] is continuous at \[x=a\]

    D)            None of these

    Correct Answer: B

    Solution :

               \[\underset{x\to 0}{\mathop{\lim }}\,f(x)=\frac{{{\sin }^{2}}ax}{{{(ax)}^{2}}}{{a}^{2}}={{a}^{2}}\] and \[f(0)=1.\]            Hence \[f(x)\] is discontinuous at \[x=0\], when \[a\ne 0\].


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