№2. Выполните действия: 1) \(\frac{5}{26}+\frac{11}{26}+\frac{7}{26}\); 3) 1-\(\frac{15}{17}\); 2) 5\(\frac{8}{21}\)-2\(\frac{3}{21}\)+1\(\frac{5}{21}\); 4) 6\(\frac{4}{11}\)-3\(\frac{7}{11}\)

Решение:

1. \(\frac{5}{26}+\frac{11}{26}+\frac{7}{26} = \frac{5+11+7}{26} = \frac{23}{26}\)
2. \(1-\frac{15}{17} = \frac{17}{17} - \frac{15}{17} = \frac{17-15}{17} = \frac{2}{17}\)
3. \(5\frac{8}{21}-2\frac{3}{21}+1\frac{5}{21} = (5-2+1) + (\frac{8}{21} - \frac{3}{21} + \frac{5}{21}) = 4 + \frac{8-3+5}{21} = 4 + \frac{10}{21} = 4\frac{10}{21}\)
4. \(6\frac{4}{11}-3\frac{7}{11} = 5\frac{15}{11}-3\frac{7}{11} = (5-3) + (\frac{15}{11} - \frac{7}{11}) = 2 + \frac{15-7}{11} = 2 + \frac{8}{11} = 2\frac{8}{11}\)

Ответ: 1) \(\frac{23}{26}\); 2) \(\frac{2}{17}\); 3) \(4\frac{10}{21}\); 4) \(2\frac{8}{11}\)