Railways Quantitative Aptitude Simplification Sample Paper Simplification Sample Test Paper-3

  • question_answer
    If \[x=3\sqrt{3}+\sqrt{26}\]  find the value of \[\frac{1}{2}\left( x+\frac{1}{x} \right)\]

    A)  \[\frac{1}{2}\]             

    B)  \[\sqrt{3}\]     

    C)  3        

    D)  \[3\sqrt{3}\]

    Correct Answer: D

    Solution :

    [d] \[x=3\sqrt{3}+\sqrt{26}\] \[\frac{1}{x}=\frac{1}{3\sqrt{3}+\sqrt{26}}\times \frac{3\sqrt{3}-\sqrt{26}}{3\sqrt{3}-\sqrt{26}}\] \[\frac{3\sqrt{3}-\sqrt{26}}{(27)-(26)}=3\sqrt{3}-\sqrt{26}\] \[\therefore \,\,\,\frac{1}{2}\left( x+\frac{1}{x} \right)=\frac{1}{2}\left[ (3\sqrt{3}+\sqrt{26})+(3\sqrt{3}-\sqrt{26}) \right]\] \[=\frac{1}{2}\times 6\sqrt{3}=3\sqrt{3}\]


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