Question

A20,3+A40,1 analise combinatotia

Answer 1

$A_{20,3}+A_{40,1}=\dfrac{20!}{(20-3)!}+\dfrac{40!}{(40-1)!}\\\\\\A_{20,3}+A_{40,1}=\dfrac{20!}{17!}+\dfrac{40!}{39!}\\\\\\A_{20,3}+A_{40,1}=\dfrac{20\cdot19\cdot18\cdot17!}{17!}+\dfrac{40\cdot39!}{39!}\\\\\\A_{7,4}=20\cdot19\cdot18+40\\\\\boxed{A_{20,3}+A_{40,1}=6880}$

Answer 2

Resposta:

A 20,3 = 20!/(20 - 3)! = 20!/17! = 20×19×18×17/17!

(cancela o número 17)

20×19×18

20× 19 = 380 × 18 = 6840

_________________________________________

A 40, 1 = 40!/(40 - 39)! = 40×39/39!

(cancela o número 39)

=40

6840+ 40 = 6880

A 20,3 + A 40,1 = 6880