Question

Determine o valor de n na equação $\frac{n!}{(n-3)!} = 720$

Answer 1

n!/(n-3)! = 720

n(n-1)(n-2)(n-3)!/(n-3)! = 720

n(n-1)(n-2) = 10(9)(8)

n(n-1)(n-2) = 10(10-1)(10-2)

===> n=10