SSC Sample Paper Mock Test-9 SSC CGL Tear-II Paper-1

  • question_answer
    The value of \[\sqrt{11+2\sqrt{30}}-\frac{1}{\sqrt{11+2\sqrt{30}}}\] is   

    A)  \[2\sqrt{5}\]

    B)  \[2\sqrt{6}\]

    C)  \[1+\sqrt{6}\]

    D)  \[1+\sqrt{5}\]

    Correct Answer: A

    Solution :

    \[\sqrt{11+2\sqrt{30}}-\frac{1}{\sqrt{11+2\sqrt{30}}}\]
    \[=\sqrt{6+5+2\sqrt{5}\sqrt{6}}-\frac{1}{\sqrt{11+2\sqrt{30}}}\]
    \[=\sqrt{{{(\sqrt{6})}^{2}}+{{(\sqrt{5})}^{2}}+2\sqrt{5}\sqrt{6}}-\sqrt{{{(\sqrt{6})}^{2}}+{{(\sqrt{5})}^{2}}+2\sqrt{5}\sqrt{6}}\]
    \[=\sqrt{{{(\sqrt{6}+\sqrt{5})}^{2}}}-\frac{1}{\sqrt{{{(\sqrt{6}+\sqrt{5})}^{2}}}}\]
    \[=\sqrt{6+}\sqrt{5}-\frac{1}{\sqrt{6}+\sqrt{5}}\times \frac{\sqrt{6}-\sqrt{5}}{\sqrt{6}-\sqrt{5}}\]
    \[=\sqrt{6}+\sqrt{5}-\frac{(\sqrt{6}-\sqrt{5})}{6-5}\]
    \[=\sqrt{6}+\sqrt{5}-(\sqrt{6}-\sqrt{5})\]
    \[=\sqrt{6}+\sqrt{5}-\sqrt{6}+\sqrt{5}\]
    \[=2\sqrt{5}\]


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