JEE Main & Advanced Sample Paper JEE Main - Mock Test - 30

  • question_answer
    If\[f(x)=\frac{x-{{e}^{x}}+\cos 2x}{{{x}^{2}}},x\ne 0\]is continuous at \[x=0\], then

    A) \[f(0)=\frac{5}{2}\]       

    B) \[[f(0)]=-2\]

    C) \[\{f(0)\}=-0.5\] 

    D) \[\{f(0)].\{f(0)\}=-1.5\]

    Correct Answer: D

    Solution :

    [d]:\[\underset{x\to 0}{\mathop{Lim}}\,\frac{x-{{e}^{x}}+1-(1-cos2x)}{{{x}^{2}}}=-\frac{1}{2}-2\] \[=-\frac{5}{2}\] hence for continuity \[f(0)=-\frac{5}{2}\] \[\therefore \]\[[f(x)]=\left[ -\frac{5}{2} \right]=-3;\{f(0)\}=\left\{ -\frac{5}{2} \right\}=\frac{1}{2}\] Hence \[[f(0)].\{f(0)\}=-\frac{3}{2}=-1.5\]


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