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If (N + 1)! = 90 [(N − 1)!], Find N. - Mathematics

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प्रश्न

If (n + 1)! = 90 [(n − 1)!], find n.

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उत्तर

(n + 1)! = 90 [(n − 1)!]

\[\Rightarrow\](n + 1)\[\times\](n)\[\times\](n−1)! = 90[(n − 1)!]
\[\Rightarrow\](+ 1)\[\times\](n) = 90
\[\Rightarrow\](n + 1)\[\times\](n) = 10\[\times\] 9
On comparing, we get:
n = 9

 

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Factorial N (N!) Permutations and Combinations
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अध्याय 16: Permutations - Exercise 16.1 [पृष्ठ ४]

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आरडी शर्मा Mathematics [English] Class 11
अध्याय 16 Permutations
Exercise 16.1 | Q 8 | पृष्ठ ४

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