Контрольные задания
Вопрос:Фото задания: Вычислите: 4/7 + 5/6; 5/18 + 7/30; 5/12 + 2/15; 15/19 + 27/38; 6/7 + 9/14; 6/7 − 9/14; 5/20 − 5/12; 9/9 − 3/8; 7/18 − 1/15.Фото задания

Ответ:

  1. Приводим дроби к общему знаменателю: \(\frac{4}{7}+\frac{5}{6}=\frac{24}{42}+\frac{35}{42}=\frac{59}{42}\).

  2. \(\frac{5}{18}+\frac{7}{30}=\frac{25}{90}+\frac{21}{90}=\frac{46}{90}=\frac{23}{45}\).

  3. \(\frac{5}{12}+\frac{2}{15}=\frac{25}{60}+\frac{8}{60}=\frac{33}{60}=\frac{11}{20}\).

  4. \(\frac{15}{19}+\frac{27}{38}=\frac{30}{38}+\frac{27}{38}=\frac{57}{38}=\frac{3}{2}\).

  5. \(\frac{6}{7}+\frac{9}{14}=\frac{12}{14}+\frac{9}{14}=\frac{21}{14}=\frac{3}{2}\).

  6. \(\frac{6}{7}-\frac{9}{14}=\frac{12}{14}-\frac{9}{14}=\frac{3}{14}\).

  7. \(\frac{5}{20}-\frac{5}{12}=\frac{1}{4}-\frac{5}{12}=\frac{3}{12}-\frac{5}{12}=-\frac{1}{6}\).

  8. \(\frac{9}{9}-\frac{3}{8}=1-\frac{3}{8}=\frac{5}{8}\).

  9. \(\frac{7}{18}-\frac{1}{15}=\frac{35}{90}-\frac{6}{90}=\frac{29}{90}\).

Ответ: \(\frac{59}{42};\ \frac{23}{45};\ \frac{11}{20};\ \frac{3}{2};\ \frac{3}{2};\ \frac{3}{14};\ -\frac{1}{6};\ \frac{5}{8};\ \frac{29}{90}\).