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JEE Main & Advanced Sample Paper JEE Main - Mock Test - 16

  • question_answer
    In how many ways n books can be arranged in a row so that two specified books are not together?

    A) \[n!-(n-2)!\]        

    B)        \[(n-2)!(n-2)\]

    C) \[n!-2(n-1)\]       

    D) \[(n-2)n!\]

    Correct Answer: B

    Solution :

    [b]: Total number of arrangements of n books = n!. If two specified books always together then number of ways \[=(n-1)!\times 2\] Hence required number of ways \[=n!-(n-1)!\times 2\] \[=n(n-1)!-(n-1)!\times 2=(n-1)!(n-2)\].


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