Railways R.R.C. (Delhi) Solved Paper Held on 1st Shift 23-11-2014

  • question_answer The square root of \[(7+3\sqrt{5})(7-3\sqrt{5})\]is­­­­­­??

    A) \[\sqrt{5}\]                                

    B) 2

    C) 4                                 

    D) \[3\sqrt{5}\]

    Correct Answer: B

    Solution :

    \[\sqrt{(7+3\sqrt{5})(7-3\sqrt{5})=\sqrt{49-9\times 5}}\] \[=\sqrt{49-45}\] \[=\sqrt{4}=2\]


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