Question

21! - 18!/ 19! como calcular esse factorial?

Answer 1

21!-18!/19!
21.20.19!-18!/19! (corta)
21.20-18!
420-18!

Answer 2

Na falta de esclarecimento
 
                  $\frac{21!-18!}{19!} \\ \\ = \frac{21.20.19.18!-18!}{19.18!} \\ \\= \frac{18!(21.29.19 - 1)}{19.18!} \\ \\ = \frac{21.20.19-1}{19} \\ \\ = \frac{7980-1}{19} \\ \\ = \frac{7979}{19}$