Tentukan nilai n pada persamaan P(n+1,3) = P(n,4).
Pembahasan:
P(n+1,3) = P(n,4)
(n + 1) ! / (n + 1 – 3) ! = n ! / (n – 4) !
((n + 1) . n !) / ((n – 2) . (n – 3) . (n – 4) !) = n ! / (n – 4) !
(n + 1) / ((n – 2) . (n – 3)) = 1/1
n² – 5n + 6 = n + 1
n² – 5n – n + 6 – 1 = 0
n² – 6n + 5 = 0
(n – 5) . (n – 1) = 0
n – 1 = 0
n = 1
n – 5 = 0
n = 5
Syarat n > 4
Jadi, nilai n = 5
