SSC Sample Paper Mock Test-14 SSC CGL Tear-II Paper-1

  • question_answer
    If \[x=\frac{\sqrt{3}}{2},\] then the value of\[\left( \frac{\sqrt{1+x}+\sqrt{1-x}}{\sqrt{1+x}-\sqrt{1-x}} \right)\]is

    A)  \[-\,\,\sqrt{3}\]

    B)  \[-\,\,1\]

    C)  \[1\]

    D)  \[\sqrt{3}\]

    Correct Answer: D

    Solution :

    \[x=\frac{\sqrt{3}}{2}\]\[\Rightarrow \]\[\frac{1}{x}=\frac{2}{\sqrt{3}}\]
    By componendo and dividendo,
    \[\frac{1+x}{1-x}=\frac{2+\sqrt{3}}{2-\sqrt{3}}=\frac{{{(2+\sqrt{3})}^{2}}}{(2-\sqrt{3})(2+\sqrt{3})}=\frac{{{(2+\sqrt{3})}^{2}}}{4-3}\]
    \[\Rightarrow \]\[\frac{1+x}{1-x}={{(2+\sqrt{3})}^{2}}\]\[\therefore \]\[\frac{\sqrt{1+x}}{\sqrt{1-x}}=\frac{2+\sqrt{3}}{1}\]
    Again, by componendo and dividendo,
    \[\frac{\sqrt{1+x}+\sqrt{1-x}}{\sqrt{1+x}-\sqrt{1-x}}=\frac{2+\sqrt{3}+1}{2+\sqrt{3}-1}\]
    \[=\frac{3+\sqrt{3}}{\sqrt{3}+1}=\frac{\sqrt{3}(\sqrt{3}+1)}{\sqrt{3}+1}=-\,\,\sqrt{3}\]


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