Контрольные задания
Вопрос:Фото задания: Блок 3. Вычислите: (9/10 − 7/15) · 3; (3/4 − 1/6) · 3; (2 1/4 − 1 3/19) · 19; (1/13 − 2 3/4) · 26; (1/5 + 8/15) · 6; (5/22…Фото задания

Ответ:

  1. Приводим дроби к общему знаменателю: \(\left(\frac{9}{10}-\frac{7}{15}\right)\cdot3=\left(\frac{27}{30}-\frac{14}{30}\right)\cdot3=\frac{13}{30}\cdot3=\frac{13}{10}\).
  2. \(\left(\frac{3}{4}-\frac{1}{6}\right)\cdot3=\left(\frac{9}{12}-\frac{2}{12}\right)\cdot3=\frac{7}{12}\cdot3=\frac{7}{4}\).
  3. Переводим смешанные числа в неправильные дроби: \(\left(2\frac{1}{4}-1\frac{3}{19}\right)\cdot19=\left(\frac{9}{4}-\frac{22}{19}\right)\cdot19=\frac{83}{76}\cdot19=\frac{83}{4}\).
  4. \(\left(\frac{1}{13}-2\frac{3}{4}\right)\cdot26=\left(\frac{1}{13}-\frac{11}{4}\right)\cdot26=\left(-\frac{139}{52}\right)\cdot26=-\frac{139}{2}\).
  5. \(\left(\frac{1}{5}+\frac{8}{15}\right)\cdot6=\left(\frac{3}{15}+\frac{8}{15}\right)\cdot6=\frac{11}{15}\cdot6=\frac{22}{5}\).
  6. \(\left(\frac{5}{22}-\frac{8}{11}\right)\cdot\frac{11}{5}=\left(\frac{5}{22}-\frac{16}{22}\right)\cdot\frac{11}{5}=-\frac{1}{2}\cdot\frac{11}{5}=-\frac{11}{10}\).
  7. \(\left(\frac{9}{17}-\frac{11}{34}\right)\cdot\frac{17}{2}=\frac{7}{34}\cdot\frac{17}{2}=\frac{7}{4}\).
  8. \(\left(\frac{17}{15}-\frac{1}{12}\right)\cdot\frac{20}{3}=\frac{63}{60}\cdot\frac{20}{3}=\frac{21}{20}\cdot\frac{20}{3}=7\).
  9. \(\left(\frac{10}{13}+\frac{15}{4}\right)\cdot\frac{26}{5}=\frac{235}{52}\cdot\frac{26}{5}=\frac{47}{2}\).
  10. \(\left(\frac{5}{26}-\frac{3}{25}\right)\cdot\frac{13}{2}=\frac{47}{650}\cdot\frac{13}{2}=\frac{47}{100}\).