SSC Sample Paper SSC CGL - Sample Paper-3

  • question_answer
    If \[x=7-4\sqrt{3},\] then \[\sqrt{x}+\frac{1}{\sqrt{x}}\] is equal to

    A)  1                                

    B)  2         

    C)  3                                

    D)  4

    Correct Answer: D

    Solution :

    \[x=7-4\sqrt{3}\] \[\therefore \]      \[\sqrt{x}=\sqrt{7-4\sqrt{3}}\]                   \[=\sqrt{7-2\times 2\times \sqrt{3}}\]                   \[=\sqrt{4+3-2\times 2\times \sqrt{3}}\]                   \[=\sqrt{{{(2-\sqrt{3})}^{2}}}=2-\sqrt{3}\] \[\therefore \]      \[\frac{1}{\sqrt{x}}=\frac{1}{2-\sqrt{3}}\]                   \[=\frac{1}{2-\sqrt{3}}\times \frac{2+\sqrt{3}}{2+\sqrt{3}}=\frac{2+\sqrt{3}}{4-3}\]                   \[=2+\sqrt{3}\] \[\therefore \]      \[\sqrt{x}+\frac{1}{\sqrt{x}}\]\[=2-\sqrt{3}+2+\sqrt{3}=4\]


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