Проверочная работа № 2 1 Вычислите: a) \(\frac{3}{4} + \frac{4}{5}\); б) \(\frac{2}{3} + \frac{1}{7}\); в) \(\frac{2}{13} + 0\); г) \(\frac{5}{9} + \frac{2}{11}\); д) \(\frac{5}{12} + \frac{3}{4}\); e) \(\frac{5}{6} + \frac{7}{8}\).

Выполним вычисления: a) \(\frac{3}{4} + \frac{4}{5}\) = \(\frac{3 \cdot 5}{4 \cdot 5} + \frac{4 \cdot 4}{5 \cdot 4}\) = \(\frac{15}{20} + \frac{16}{20}\) = \(\frac{15 + 16}{20}\) = \(\frac{31}{20}\) = 1 \(\frac{11}{20}\). б) \(\frac{2}{3} + \frac{1}{7}\) = \(\frac{2 \cdot 7}{3 \cdot 7} + \frac{1 \cdot 3}{7 \cdot 3}\) = \(\frac{14}{21} + \frac{3}{21}\) = \(\frac{14 + 3}{21}\) = \(\frac{17}{21}\). в) \(\frac{2}{13} + 0\) = \(\frac{2}{13}\). г) \(\frac{5}{9} + \frac{2}{11}\) = \(\frac{5 \cdot 11}{9 \cdot 11} + \frac{2 \cdot 9}{11 \cdot 9}\) = \(\frac{55}{99} + \frac{18}{99}\) = \(\frac{55 + 18}{99}\) = \(\frac{73}{99}\). д) \(\frac{5}{12} + \frac{3}{4}\) = \(\frac{5}{12} + \frac{3 \cdot 3}{4 \cdot 3}\) = \(\frac{5}{12} + \frac{9}{12}\) = \(\frac{5 + 9}{12}\) = \(\frac{14}{12}\) = \(\frac{7}{6}\) = 1 \(\frac{1}{6}\). e) \(\frac{5}{6} + \frac{7}{8}\) = \(\frac{5 \cdot 4}{6 \cdot 4} + \frac{7 \cdot 3}{8 \cdot 3}\) = \(\frac{20}{24} + \frac{21}{24}\) = \(\frac{20 + 21}{24}\) = \(\frac{41}{24}\) = 1 \(\frac{17}{24}\). Ответ: а) 1 \(\frac{11}{20}\); б) \(\frac{17}{21}\); в) \(\frac{2}{13}\); г) \(\frac{73}{99}\); д) 1 \(\frac{1}{6}\); е) 1 \(\frac{17}{24}\).