JCECE Engineering JCECE Engineering Solved Paper-2013

  • question_answer
    If\[x>0\], then solution of\[\left| x+\frac{1}{x} \right|<4\]is

    A) \[-2-\sqrt{3}<x<-2+\sqrt{3}\]

    B) \[2-\sqrt{3}<x<7+\sqrt{3}\]

    C) \[2-\sqrt{3}<x<2+\sqrt{3}\]

    D)  None of the above

    Correct Answer: A

    Solution :

    \[\because \]     \[\left| x+\frac{1}{x} \right|<4\] \[\Rightarrow \]               \[\frac{{{x}^{2}}+1}{|x|}<4\] \[\Rightarrow \]               \[|x{{|}^{2}}-\,\,4|x|+1<0\] \[\Rightarrow \]               \[{{(|x|-2)}^{2}}<3\] \[\Rightarrow \]               \[{{(|x|-2)}^{2}}<{{(\sqrt{3})}^{2}}\] \[\Rightarrow \]               \[||x|-2<\sqrt{3}\] \[\Rightarrow \]               \[-\sqrt{3}<(|x|-2)<3\] \[\Rightarrow \]               \[2-\sqrt{3}<x<2+\sqrt{3}\] When\[x>0,\,\,2-\sqrt{3}<x<2+\sqrt{3}\] and when\[x<0,\,\,-2-\sqrt{3}<x<-2+\sqrt{3}\]


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