Question

Se An,5 = 6 · An,3
(Arranjo)
Calcule n

Answer 1

Boa noite Alyssa

A(n,5) = 6*A(n,3) 

n!(n - 5)! = 6*n!/(n - 3)!

(n - 3)!/(n - 5)! = 6

(n - 3)*(n - 4)*(n - 5)!/(n - 5)! = 6 

n² - 7n + 12 =  6 
n² - 7n + 6 = 0

delta
d² = 49 - 24 = 25
d = 5

n = (7 + 5)/2 = 12/2 = 6 

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