Проверочная работа № 2 1 Вычислите: а) 3/5 + 4/5; в) 2/13 + 0; д) 5/12 + 3/4; б) 2/3 + 1/7; г) 5/9 + 2/11; е) 5/6 + 7/8.

1. а) $$ \frac{3}{5} + \frac{4}{5} = \frac{3+4}{5} = \frac{7}{5} = 1\frac{2}{5} $$
2. в) $$ \frac{2}{13} + 0 = \frac{2}{13} $$
3. д) $$ \frac{5}{12} + \frac{3}{4} = \frac{5}{12} + \frac{3 \cdot 3}{4 \cdot 3} = \frac{5}{12} + \frac{9}{12} = \frac{5+9}{12} = \frac{14}{12} = \frac{7}{6} = 1\frac{1}{6} $$
4. б) $$ \frac{2}{3} + \frac{1}{7} = \frac{2 \cdot 7}{3 \cdot 7} + \frac{1 \cdot 3}{7 \cdot 3} = \frac{14}{21} + \frac{3}{21} = \frac{14+3}{21} = \frac{17}{21} $$
5. г) $$ \frac{5}{9} + \frac{2}{11} = \frac{5 \cdot 11}{9 \cdot 11} + \frac{2 \cdot 9}{11 \cdot 9} = \frac{55}{99} + \frac{18}{99} = \frac{55+18}{99} = \frac{73}{99} $$
6. е) $$ \frac{5}{6} + \frac{7}{8} = \frac{5 \cdot 4}{6 \cdot 4} + \frac{7 \cdot 3}{8 \cdot 3} = \frac{20}{24} + \frac{21}{24} = \frac{20+21}{24} = \frac{41}{24} = 1 \frac{17}{24} $$

Ответ: а) 7/5 = 1 2/5; в) 2/13; д) 14/12 = 7/6 = 1 1/6; б) 17/21; г) 73/99; е) 41/24 = 1 17/24.