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Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-27

  • question_answer
    If\[\left( {{x}^{2}}+\frac{1}{{{x}^{2}}} \right)=66,\]then \[\left( x-\frac{1}{x} \right)\]is equal to

    A)  6                    

    B)  12

    C)  8                    

    D)  9

    Correct Answer: C

    Solution :

    \[\because \]\[{{x}^{2}}+\frac{1}{{{x}^{2}}}=66=64+2\] \[{{x}^{2}}+\frac{1}{{{x}^{2}}}-2=64\] \[{{\left[ x-\frac{1}{x} \right]}^{2}}={{(8)}^{2}}\Rightarrow x-\frac{1}{x}=8\]


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