Question

Determine o valor de n na equação :

n! = 56
(n-2)!

Answer 1

n! / (n-2)! = 56
n.(n-1)(n-2)! / (n-2)! = 56
n(n-1) = 56
n² - n -56 = 0

∆= 1 + 224
∆= 225
√∆= 15

n' = 1 + 15/2
n' = 8

n" = 1 - 15/2
n" = -7


n vale 8