A) \[n\,!\,-(n-2)\,!\]
B) \[(n-1)\,!\,(n-2)\]
C) \[n\,!-2(n-1)\]
D) \[(n-2)\,n!\]
Correct Answer: B
Solution :
Total number of arrangements of \[n\] books \[^{6}{{P}_{5}}\times 5\ !=86400\]. If two specified books always together then number of ways \[=(n-1)\ !\ \times 2\] Hence required number of ways \[=n\ !-(n-1)\ !\ \times 2\] \[=n(n-1)\ !\ -(n-1)\ \times 2=(n-1)\ !\ (n-2)\].You need to login to perform this action.
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