9. Вычислите по алгоритму 17 13/21 -7 3/21 -2 4/21 +1 2/21 ?

Выполним вычисления по шагам: Шаг 1: $$17 \frac{13}{21} - 7 \frac{3}{21}$$ $$17 \frac{13}{21} - 7 \frac{3}{21} = (17 - 7) + (\frac{13}{21} - \frac{3}{21}) = 10 + \frac{10}{21} = 10 \frac{10}{21}$$ Шаг 2: $$10 \frac{10}{21} - 2 \frac{4}{21}$$ $$10 \frac{10}{21} - 2 \frac{4}{21} = (10 - 2) + (\frac{10}{21} - \frac{4}{21}) = 8 + \frac{6}{21} = 8 \frac{6}{21}$$ Шаг 3: $$8 \frac{6}{21} + 1 \frac{2}{21}$$ $$8 \frac{6}{21} + 1 \frac{2}{21} = (8 + 1) + (\frac{6}{21} + \frac{2}{21}) = 9 + \frac{8}{21} = 9 \frac{8}{21}$$ Ответ: 2) $$9 \frac{8}{21}$$