J & K CET Engineering J and K - CET Engineering Solved Paper-2007

  • question_answer
    At \[x=\frac{3}{2}\] the function \[f(x)=\frac{|2x-3|}{2x-3}\] is

    A)  continuous   

    B)  discontinuous

    C)  differentiable 

    D)  non-zero

    Correct Answer: B

    Solution :

    Given, \[f(x)=\frac{|2x-3|}{2x-3}\] \[\left\{ \begin{matrix}    \frac{2x-3}{2x-3}, & if & x\ge \frac{3}{2}  \\    \frac{-(2x-3)}{2x-3}, & if & x<\frac{3}{2}  \\ \end{matrix} \right.\] \[\left\{ \begin{matrix}    1, & if & x\ge \frac{3}{2}  \\    -1, & if & x<\frac{3}{2}  \\ \end{matrix} \right.\] Now,   \[RHL=\underset{x\to \frac{{{3}^{+}}}{2}}{\mathop{\lim }}\,\,f(x)=\underset{x\to \frac{{{3}^{+}}}{2}}{\mathop{\lim }}\,1=1\] and \[LHL=\underset{x\to \frac{{{3}^{-}}}{2}}{\mathop{\lim }}\,\,f(x)=\underset{x\to \frac{{{3}^{-}}}{2}}{\mathop{\lim }}\,(-1)=-1\] \[\because \] \[RHL\ne LHL\] \[\therefore \]     \[f(x)\] is discontinuous at \[x=\frac{3}{2}\].


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