Question

Exercício de contagem.

Grata.

Answer 1

Oi Mari

a) 7!/4! = 7*6*5*4!/4! = 7*6*5 = 210 

b) 3!*7!/4!6! 

3!/4! = 1/4,    7!/6! = 7

3!*7!/4!6! = 7/4 

Answer 2

Boa tarde Mari!

Solução!

$A= \dfrac{7!}{4!}\\\\\\\ A= \dfrac{7\times6\times5\times4!}{4!}\\\\\\\ A=7\times6\times5\\\\\\\ \boxed{A=210}$


$B= \dfrac{3! \times 7!}{4! \times 6!}\\\\\\\ B= \dfrac{3! \times 7\times6!}{4! \times3! 6!}\\\\\\\ B=\dfrac{3! \times 7\times6!}{4\times3! \times 6!}\\\\\\\ \boxed{B= \dfrac{7}{4}}$

Boa tarde!
Bons estudos!