\(\boxed{\mathbf{2.407}\mathbf{.\ ОК\ ГДЗ - домашка\ на\ }5}\)
Пояснение.
Решение.
\[\textbf{а)}\ 9 \cdot \frac{1}{9} = 1\]
\[\textbf{б)}\ \frac{1}{23} \cdot 23 = 1\]
\[\textbf{в)}\ \frac{13}{101} \cdot \frac{101}{13} = 1\]
\[\textbf{г)}\ \frac{99}{646} \cdot \frac{646}{99} = 1\]
\[\textbf{д)}\ \frac{5}{12} \cdot 2\frac{2}{5} = \frac{5}{12} \cdot \frac{12}{5} = 1\]
\[\textbf{е)}\ 2\frac{5}{6} \cdot \frac{6}{17} = \frac{17}{6} \cdot \frac{6}{17} = 1\]
\[\textbf{ж)}\ \frac{4}{15} \cdot 3,75 = \frac{4}{15} \cdot \frac{375}{100} =\]
\[= \frac{4}{15} \cdot \frac{15}{4} = 1\]
\[\textbf{з)}\ 0,6 \cdot 1\frac{2}{3} = \frac{6}{10} \cdot \frac{5}{3} = \frac{3}{5} \cdot \frac{5}{3} = 1\]