Контрольные задания > 20:07 = 100 3)- 4)= 984 из 984 4537-2578/1 12673457 26 8 16 이 = 37 11 77 Нат Ник 15:32 2 5.21.9 7 15 24 4.8.20 = = 6 3 28 13.3.28 79 30 = 1440.20 3 50 5 4 117.10.5 20 34 2 =
Вопрос:

20:07 = 100 3)- 4)= 984 из 984 4537-2578/1 12673457 26 8 16 이 = 37 11 77 Нат Ник 15:32 2 5.21.9 7 15 24 4.8.20 = = 6 3 28 13.3.28 79 30 = 1440.20 3 50 5 4 117.10.5 20 34 2 =

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Ответ:

Краткое пояснение: Решаем примеры на умножение и деление дробей.

  1. \(\frac{2}{5} \cdot \frac{3}{4} = \frac{2 \cdot 3}{5 \cdot 4} = \frac{6}{20} = \frac{3}{10}\)

  2. \(\frac{1}{7} \cdot \frac{2}{3} = \frac{1 \cdot 2}{7 \cdot 3} = \frac{2}{21}\)

  3. \(\frac{4}{5} \cdot \frac{6}{5} = \frac{4 \cdot 6}{5 \cdot 5} = \frac{24}{25}\)

  4. \(\frac{1}{8} \cdot \frac{7}{9} = \frac{1 \cdot 7}{8 \cdot 9} = \frac{7}{72}\)

  5. \(\frac{2}{3} \cdot \frac{6}{7} = \frac{2 \cdot 6}{3 \cdot 7} = \frac{12}{21} = \frac{4}{7}\)

  6. \(\frac{4}{5} : \frac{1}{2} = \frac{4}{5} \cdot \frac{2}{1} = \frac{4 \cdot 2}{5 \cdot 1} = \frac{8}{5} = 1 \frac{3}{5}\)

  7. \(\frac{3}{7} : \frac{6}{7} = \frac{3}{7} \cdot \frac{7}{6} = \frac{3 \cdot 7}{7 \cdot 6} = \frac{21}{42} = \frac{1}{2}\)

  8. \(\frac{1}{2} : \frac{3}{4} = \frac{1}{2} \cdot \frac{4}{3} = \frac{1 \cdot 4}{2 \cdot 3} = \frac{4}{6} = \frac{2}{3}\)

  9. \(\frac{5}{7} : \frac{5}{7} = \frac{5}{7} \cdot \frac{7}{5} = \frac{5 \cdot 7}{7 \cdot 5} = \frac{35}{35} = 1\)

  10. \(\frac{8}{11} : \frac{16}{77} = \frac{8}{11} \cdot \frac{77}{16} = \frac{8 \cdot 77}{11 \cdot 16} = \frac{616}{176} = \frac{7}{2} = 3 \frac{1}{2}\)

  11. \(\frac{5}{7} \cdot \frac{21}{15} : \frac{9}{24} = \frac{5}{7} \cdot \frac{21}{15} \cdot \frac{24}{9} = \frac{5 \cdot 21 \cdot 24}{7 \cdot 15 \cdot 9} = \frac{2520}{945} = \frac{8}{3} = 2 \frac{2}{3}\)

  12. \(\frac{4}{5} \cdot \frac{8}{10} : \frac{20}{2} = \frac{4}{5} \cdot \frac{8}{10} \cdot \frac{2}{20} = \frac{4 \cdot 8 \cdot 2}{5 \cdot 10 \cdot 20} = \frac{64}{1000} = \frac{8}{125}\)

  13. \(\frac{6}{7} \cdot \frac{3}{9} : \frac{28}{30} = \frac{6}{7} \cdot \frac{3}{9} \cdot \frac{30}{28} = \frac{6 \cdot 3 \cdot 30}{7 \cdot 9 \cdot 28} = \frac{540}{1764} = \frac{15}{49}\)

  14. \(\frac{40}{50} \cdot \frac{20}{5} : \frac{3}{4} = \frac{40}{50} \cdot \frac{20}{5} \cdot \frac{4}{3} = \frac{40 \cdot 20 \cdot 4}{50 \cdot 5 \cdot 3} = \frac{3200}{750} = \frac{64}{15} = 4 \frac{4}{15}\)

  15. \(\frac{17}{20} \cdot \frac{10}{34} : \frac{5}{2} = \frac{17}{20} \cdot \frac{10}{34} \cdot \frac{2}{5} = \frac{17 \cdot 10 \cdot 2}{20 \cdot 34 \cdot 5} = \frac{340}{3400} = \frac{1}{10}\)

Ответ: 1) \(\frac{3}{10}\); 2) \(\frac{2}{21}\); 3) \(\frac{24}{25}\); 4) \(\frac{7}{72}\); 5) \(\frac{4}{7}\); 6) 1 \(\frac{3}{5}\); 7) \(\frac{1}{2}\); 8) \(\frac{2}{3}\); 9) 1; 10) 3 \(\frac{1}{2}\); 11) 2 \(\frac{2}{3}\); 12) \(\frac{8}{125}\); 13) \(\frac{15}{49}\); 14) 4 \(\frac{4}{15}\); 15) \(\frac{1}{10}\)

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