JEE Main & Advanced Mathematics Limits, Continuity and Differentiability Question Bank Mock Test - Continuity and Differentiability

  • question_answer
    Which of the following functions have finite number of points of discontinuity in R ([.] represents the greatest integer function)?

    A) \[\operatorname{tanx}\]

    B) \[x[x]\]

    C) \[\frac{\left| x \right|}{x}\]         

    D) \[\sin [\pi x]\]  

    Correct Answer: C

    Solution :

    [c] \[f(x)=\tan x\] is discontinuous when \[x=(2n+1)\pi /2,n\in Z\] \[f(x)=x[x]\] is discontinuous when \[x=k,k\in Z\] \[f(x)=\sin [n\,\pi x]\] is discontinuous when \[n\pi x=k,k\in Z\] Thus, all the above functions have infinite number of points of discontinuity. But\[f(x)=\frac{\left| x \right|}{x}\]is discontinuous when x=0 only.


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