Question

Q.4 Find n, if: 42 x (n-1)!.
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Answer 1

Step-by-step explanation:

(n+1)!=42(n−1)!

⇒(n+1)(n)(n−1)!=42(n−1)

⇒n

2

+n−42=0

⇒n

2

+7n−6n−42=0

⇒n(n+7)−6(n+7)=0

⇒(n+7)(n−6)=0

⇒n=−7,n=6

∴n=6.