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Railways Sample Paper RRBs Assistant Loco Pilot and Technician CBT STAGE-I Sample Paper-30

  • question_answer
    If\[x-\frac{1}{x}=3.\]The value of\[{{x}^{2}}+\frac{1}{{{x}^{2}}}\]

    A)  2                    

    B)  12   

    C)  10                   

    D)  11

    Correct Answer: D

    Solution :

    \[\because x-\frac{1}{x}=3\] On square both the Side. \[{{\left( x-\frac{1}{x} \right)}^{2}}={{(3)}^{2}}\] \[\Rightarrow \]   \[{{x}^{2}}+\frac{1}{{{x}^{2}}}-2\cdot x\cdot \frac{1}{x}=9\] \[\therefore \]      \[{{x}^{2}}+\frac{1}{{{x}^{2}}}=9+2=11\]


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