Question

Resolva a equação
 A 5,x = C 5,5 - x

Answer 1

$A_{5,x}=C_{5,5-x}\\ \\ \frac{5!}{(5-x)!}=\frac{5!}{(5-5+x)!(5-x)!}\\ \\ \frac{5!}{(5-x)!}=\frac{5!}{x!(5-x)!}\\ \\ \frac{1}{1}=\frac{1}{x!}\\ \\ x!=1\\ \\ \boxed{x=1 \ \ ou \ \ \ x=0}$