VIT Engineering VIT Engineering Solved Paper-2008

  • question_answer
    The value of \[f(0)\] so that \[\frac{(-{{e}^{x}}+{{2}^{x}})}{x}\]may be continuous at\[x=0\]is

    A)  \[\log \left( \frac{1}{2} \right)\]

    B)  0

    C)  4

    D)  \[-1+\log 2\]

    Correct Answer: D

    Solution :

    \[\because f(x)=\frac{-{{e}^{x}}+{{2}^{x}}}{x}\] and\[f(x)\]is continuous at x = 0 \[\therefore \] \[\underset{x\to 0}{\mathop{\lim }}\,f(x)=f(0)\] \[\Rightarrow \]\[\underset{x\to 0}{\mathop{\lim }}\,\frac{-{{e}^{x}}+{{2}^{x}}}{x}=f(0)\] \[\Rightarrow \]\[\underset{x\to 0}{\mathop{\lim }}\,\frac{-{{e}^{x}}+{{2}^{x}}\log 2}{1}=f(0)\] (using LHospitals rule) \[\Rightarrow \] \[-{{e}^{0}}+{{2}^{0}}\log 2=f(0)\] \[\Rightarrow \] \[f(0)=-1+log2\]


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