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SSC Sample Paper SSC CGL - Sample Paper-7

  • question_answer
    The value of \[{{(3+2\sqrt{2})}^{-3}}+{{(3-2\sqrt{2})}^{-3}}\]

    A)  189                             

    B)  180

    C)  108                             

    D)  198

    Correct Answer: D

    Solution :

    \[\frac{1}{{{(3+2\sqrt{2})}^{3}}}+\frac{1}{{{(3-2\sqrt{2})}^{3}}}\] \[={{(3-2\sqrt{2})}^{3}}+{{(3+2\sqrt{2})}^{3}}\] \[=27-16\sqrt{2}-54\sqrt{2}+72+27+16\sqrt{2}+54\sqrt{2}+72\]\[=27+72+27+72=198\]


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