Question

Combinação e Arranjo

C x,5 = A x,4

Answer 1

Resposta:

x=124

Explicação passo-a-passo:

$C_{x,5}=A_{x,4}\\\\\frac{x!}{5!(x-5)!}=\frac{x!}{(x-4)!} \rightarrow \frac{(x-4)!}{(x-5)!}=\frac{x!5!}{x!}\\\\\frac{(x-4)(x-5)!}{(x-5)!}=5!\rightarrow x-4=5\times4\times3\times2\times1\\\\x-4=120\rightarrow \textbf{x=124}$