Вариант 2. 1. Найдите значение выражения: 3 7 a) 유-유+규: К - 8 (Виленкин, п. 29) 19 15 19 6)90+(8-3); B) 10-(4+3)

Решение:

a) $$\frac{5}{11} - \frac{3}{11} + \frac{7}{11} = \frac{5-3+7}{11} = \frac{9}{11}$$

б) $$9 \frac{13}{19} + (8 \frac{18}{19} - 3 \frac{15}{19}) = 9 \frac{13}{19} + (8 - 3 + \frac{18-15}{19}) = 9 \frac{13}{19} + 5 \frac{3}{19} = 9 + 5 + \frac{13+3}{19} = 14 \frac{16}{19}$$

в) $$10 \frac{4}{21} - (4 \frac{10}{21} + 3 \frac{19}{21}) = 10 \frac{4}{21} - (4 + 3 + \frac{10+19}{21}) = 10 \frac{4}{21} - (7 + \frac{29}{21}) = 10 \frac{4}{21} - 7 \frac{29}{21} = 10 \frac{4}{21} - 8 \frac{8}{21} = 9 \frac{25}{21} - 8 \frac{8}{21} = 1 \frac{17}{21}$$

Ответ: a) $$\frac{9}{11}$$, б) $$14 \frac{16}{19}$$, в) $$1 \frac{17}{21}$$