If (n + 1)! = 90 [(n – 1)!], find n. – InterviewSolution

InterviewSolution

1.

If (n + 1)! = 90 [(n – 1)!], find n.

Answer»

Given :

(n + 1)! = 90 [(n – 1)!]

To Find : n ?

⇒ (n + 1) × (n) × (n-1)!

= 60 [(n – 1)!]

⇒ (n + 1) × (n) = 90

⇒ (n + 1) × (n) = 10 × 9

n = 9

Hence,

n = 9

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