\[\boxed{\text{892\ (892).}\text{\ }\text{Еуроки\ -\ ДЗ\ без\ мороки}}\]
\[\textbf{а)}\frac{20!}{18!} = \frac{18! \cdot 19 \cdot 20}{18!} = 19 \cdot 20 =\]
\[= 380;\]
\[\textbf{б)}\frac{7!}{10!} = \frac{7!}{7! \cdot 8 \cdot 9 \cdot 10} = \frac{1}{720};\]
\[\textbf{в)}\frac{50!}{49!} = \frac{49! \cdot 50}{49!} = 50;\]
\[\textbf{г)}\frac{10!}{5! \cdot 5!} = \frac{5! \cdot 6 \cdot 7 \cdot 8 \cdot 9 \cdot 10}{5! \cdot 2 \cdot 3 \cdot 4 \cdot 5} =\]
\[= 252;\]
\[\textbf{д)}\ \frac{12!}{9! \cdot 3!} = \frac{9! \cdot 10 \cdot 11 \cdot 12}{9! \cdot 2 \cdot 3} =\]
\[= 220.\]
\[\boxed{\text{892.}\text{\ }\text{ОК\ ГДЗ\ -\ домашка\ на\ 5}}\]
\[\textbf{а)}\ y \leq \frac{10}{|x|}\]
\[\textbf{б)}\ y + \left| \frac{8}{x} \right| \geq 0\]
\[y \geq - \left| \frac{8}{x} \right|\]
\[\textbf{в)}\ |y| - x^{2} + 2x \leq 1\]
\[|y| \leq x^{2} - 2x + 1\]
\[\textbf{г)}\ |y| + x^{2} - 4x \geq 4\]
\[|y| \leq x^{2} - 4x - 4\]