BCECE Engineering BCECE Engineering Solved Paper-2015

  • question_answer
    The solution set of the in equation \[\frac{1}{|x|-3}<\frac{1}{2}\] is

    A) \[(-\infty ,-5)\cup (5,\infty )\]   

    B) \[(-3,3)\]

    C) \[(-\infty ,-5)\cup (-3,3)\cup (5,\infty )\]

    D) None of the above

    Correct Answer: C

    Solution :

    We have, \[\frac{1}{|x|-3}<\frac{1}{2}\] Clearly, \[\frac{1}{|x|-3}\]is not defined for \[|x|=3,\]i.e. Now,                     \[\frac{1}{|x|-3}<\frac{1}{2}\] \[\Rightarrow \]               \[\frac{1}{|x|-3}-\frac{1}{2}<0\] \[\Rightarrow \]               \[\frac{2-|x|+3}{|x|-3}<0\] \[\Rightarrow \]               \[\frac{|x|-5}{|x|-3}>0\] \[\Rightarrow \]               \[|x|<3\] or \[|x|>5\] \[\Rightarrow \]               \[x\in (-3,3)\]or \[x\in (-\infty ,-5)\cup (5,\infty )\] \[\Rightarrow \]               \[x\in (-\infty ,-5)\cup (-3,3)\cup (5,\infty )\]


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