Q. 33.5( 6 Votes )

If 5 P(4, n) = 6

Answer :

Given: 5 P(4, n) = 6 P(5, n – 1)


To find: value of n


We know,







So, according to question:


5 P(4, n) = 6 P(5, n – 1)






(6 – n) (5 – n) = 6


30 – 6n – 5n + n2 = 6


30 – 6 – 11n + n2 = 0


n2 – 11n + 24 = 0


n2 – 8n – 3n + 24 = 0


n(n – 8) – 3(n – 8) = 0


(n – 8) (n – 3) = 0


n = 8 or 3


For, P(n, r): r ≤ n


n = 3 {for, P(4, n)}


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