Ответ:

[tex]P_{n} = n! = 1 \times 2 \times 3 \times 4 \times 5 \times \dots \times n[/tex]

[tex]A_{n}^{m} = \frac{n!}{(n - m)!} [/tex]

[tex]C_{n}^{m} = \frac{n!}{m!(n - m)!} [/tex]

[tex]P_4-2A_9^{2}+3C_8^{2} = 4! - 2 \times \frac{9!}{(9 - 2)!} + 3 \times \frac{8!}{2!(8 - 2)!} = \\ 1 \times 2 \times 3 \times 4 - 2 \times \frac{7! \times 8 \times 9}{7!} + 3 \times \frac{6! \times 7 \times 8}{1 \times 2 \times 6!} = \\ 24 - 2 \times 8 \times 9 + 3 \times \frac{7 \times 8}{2} = 24 - 144 + 84 = - 36[/tex]

Ответ: -36