Question

calcule os fatoriais (resolução)

a) 8
3

b) 6!
2!

c) n!=20. (n-2)!

Answer 1

a) 

$\dfrac{8!}{3!} \\ \\ \\ \dfrac{8 . 7 . 6 . 5 . 4 . \not 3!}{\not3!} \\ \\ \\ 8 . 7 . 6 . 5 . 4 \\ \\ \\ =\ \textgreater \ 6720$

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b)


$\dfrac{6!}{2!} \\ \\ \\ \dfrac{6. 5 . 4 . 3 . \not 2!}{\not2!} \\ \\ \\ 6 , 5 , 4 , 3 \\ \\ \\ =\ \textgreater \ 360$

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c) 

$n! = 20.(n - 2)! \\ \\ \\ n! = 20 . \dfrac{n!}{ \dfrac{n - 0}{n - 1} } \\ \\ \\ n! = \dfrac{20n!}{n^2 - n} \\ \\ \\=\ \textgreater \ \dfrac{(n^2 - n - 20 . )n!}{n^2 - n}$