Question

encontre o valor de x , tal que (2x-5)! =40320

Answer 1

observe que

40.320=8!    (8.7.6.5.4.3.2.1)

entáo

(2x-5)!=8!
eliminando o sinal de fatorial

$2x-5=8 \\ 2x=8+5 \\ 2x=13 \\ \\ x= \frac{13}{2}$