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

Проверочная работа № 2

1. Вычислим:

a) \(\frac{3}{4} + \frac{4}{5}\)

Приведем дроби к общему знаменателю 20:

\(\frac{3}{4} = \frac{3 \cdot 5}{4 \cdot 5} = \frac{15}{20}\)

\(\frac{4}{5} = \frac{4 \cdot 4}{5 \cdot 4} = \frac{16}{20}\)

\(\frac{15}{20} + \frac{16}{20} = \frac{15 + 16}{20} = \frac{31}{20} = 1\frac{11}{20}\)

в) \(\frac{2}{13} + 0 = \frac{2}{13}\)

д) \(\frac{5}{12} + \frac{3}{4}\)

Приведем дроби к общему знаменателю 12:

\(\frac{3}{4} = \frac{3 \cdot 3}{4 \cdot 3} = \frac{9}{12}\)

\(\frac{5}{12} + \frac{9}{12} = \frac{5 + 9}{12} = \frac{14}{12} = \frac{7}{6} = 1\frac{1}{6}\)

б) \(\frac{2}{3} + \frac{1}{7}\)

Приведем дроби к общему знаменателю 21:

\(\frac{2}{3} = \frac{2 \cdot 7}{3 \cdot 7} = \frac{14}{21}\)

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

\(\frac{14}{21} + \frac{3}{21} = \frac{14 + 3}{21} = \frac{17}{21}\)

г) \(\frac{5}{9} + \frac{2}{11}\)

Приведем дроби к общему знаменателю 99:

\(\frac{5}{9} = \frac{5 \cdot 11}{9 \cdot 11} = \frac{55}{99}\)

\(\frac{2}{11} = \frac{2 \cdot 9}{11 \cdot 9} = \frac{18}{99}\)

\(\frac{55}{99} + \frac{18}{99} = \frac{55 + 18}{99} = \frac{73}{99}\)

е) \(\frac{5}{6} + \frac{7}{8}\)

Приведем дроби к общему знаменателю 24:

\(\frac{5}{6} = \frac{5 \cdot 4}{6 \cdot 4} = \frac{20}{24}\)

\(\frac{7}{8} = \frac{7 \cdot 3}{8 \cdot 3} = \frac{21}{24}\)

\(\frac{20}{24} + \frac{21}{24} = \frac{20 + 21}{24} = \frac{41}{24} = 1\frac{17}{24}\)

Ответ: a) \(1\frac{11}{20}\); в) \(\frac{2}{13}\); д) \(1\frac{1}{6}\); б) \(\frac{17}{21}\); г) \(\frac{73}{99}\); e) \(1\frac{17}{24}\)