Question

Помогите пожалуйста
Алгебра 9 класс

Answer 1

Ответ:

$С ^{2}_{16} = \frac{16!}{2!(16 - 2)!} = \frac{16 \times 15 \times 14!}{1 \times 2 \times 14!} = \\ = \frac{16 \times 15}{2} = 8 \times 15 = 120$

...

$А^{2} _{6} = \frac{6!}{(6 - 2)!} = \frac{6 \times 5 \times 4!}{4!} = \\ = 6 \times 5 = 30$

...

$\frac{Р_{8} }{Р_{4} } = \frac{8!}{4!} = \frac{4! \times 5 \times 6 \times 7 \times 8}{4!} = \\ = 5 \times 6 \times 7 \times 8 = 1680$