4.300 Найдите значение произведения: a)(\frac{4}{9})\cdot(-4\frac{1}{2}); 3 B) 2,4\cdot(-\frac{3}{4}); 5 6) -4\frac{4}{5}\cdot(-3\frac{1}{3}); г) -\frac{5}{9}\cdot5,4; e) -1\frac{2}{3}\cdot0,125. д) -2,7\cdot(-1\frac{1}{9});

Ответ:

• а) \[\frac{4}{9} \cdot \left(-4\frac{1}{2}\right) = \frac{4}{9} \cdot \left(-\frac{9}{2}\right) = \frac{4 \cdot (-9)}{9 \cdot 2} = \frac{-36}{18} = -2\]
• б) \[ -4\frac{4}{5} \cdot \left(-3\frac{1}{3}\right) = -\frac{24}{5} \cdot \left(-\frac{10}{3}\right) = \frac{-24 \cdot (-10)}{5 \cdot 3} = \frac{240}{15} = 16\]
• в) \[2,4 \cdot \left(-\frac{3}{4}\right) = \frac{24}{10} \cdot \left(-\frac{3}{4}\right) = \frac{12}{5} \cdot \left(-\frac{3}{4}\right) = \frac{12 \cdot (-3)}{5 \cdot 4} = \frac{-36}{20} = -1,8\]
• г) \[-\frac{5}{9} \cdot 5,4 = -\frac{5}{9} \cdot \frac{54}{10} = -\frac{5 \cdot 54}{9 \cdot 10} = -\frac{270}{90} = -3\]
• д) \[ -2,7 \cdot \left(-1\frac{1}{9}\right) = -\frac{27}{10} \cdot \left(-\frac{10}{9}\right) = \frac{-27 \cdot (-10)}{10 \cdot 9} = \frac{270}{90} = 3\]
• е) \[ -1\frac{2}{3} \cdot 0,125 = -\frac{5}{3} \cdot \frac{125}{1000} = -\frac{5}{3} \cdot \frac{1}{8} = -\frac{5 \cdot 1}{3 \cdot 8} = -\frac{5}{24}\]