VIT Engineering VIT Engineering Solved Paper-2011

  • question_answer
    If \[D\]is the set of the \[x\] such that \[1-{{e}^{(1/x)-1}}\] is positive, then \[D\] is equal to

    A)  \[(-\,\infty ,\,1)\]

    B)  \[(-\,\infty ,\,0)\]

    C)  \[(1,\,\infty )\]

    D)  \[(-\,\infty ,\,0)\cup (1,\,\infty )\]

    Correct Answer: D

    Solution :

    We have, \[{{C}_{1}}{{C}_{2}}=5<\]sum of radii But \[{{C}_{1}}{{C}_{2}}=\]difference of radii Thus, the given circles touch each other internally. Hence, number of common tangent is only one. We have, \[1-{{e}^{\frac{1}{x}-1\,}}>0\] \[\Rightarrow \] \[{{e}^{\frac{1}{x}-1}}<1\] \[\Rightarrow \] \[\frac{1}{x}-1<\log 1\] \[\Rightarrow \] \[\frac{1}{x}-1<0\] \[\Rightarrow \] \[\frac{1}{x}<1\] \[\Rightarrow \] \[x\in (-\,\infty ,0)\cup (1,\infty )\]


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