Question

questão de Arranjo:

Ax,2 = 20

Answer 1

Boa tarde

A(x,2) = x!/(x - 2)!

x!/(x - 2)! = 20
x! = 20*(x - 2)!
x*(x - 1)*(x - 2)! = 20*(x - 2)!

x² - x - 20 = 0

delta
d² = 1 + 80 = 81
d = 9

x = (1 + 9)/2 = 10/2 = 5