Вариант Б1 1. Вычислите: a) 1,25 - 3,8; б) -0,4 - 1/8; в) -2/9 - (-1 5/6); г) 1 5/7 - (-3 11/14) + (-2 1/4).

Решение: a) \(1,25 - 3,8 = -2,55\) б) \(-0,4 - \frac{1}{8} = -\frac{4}{10} - \frac{1}{8} = -\frac{2}{5} - \frac{1}{8} = -\frac{16}{40} - \frac{5}{40} = -\frac{21}{40} = -0,525\) в) \(-\frac{2}{9} - (-1\frac{5}{6}) = -\frac{2}{9} + 1\frac{5}{6} = -\frac{2}{9} + \frac{11}{6} = -\frac{4}{18} + \frac{33}{18} = \frac{29}{18} = 1\frac{11}{18}\) г) \(1\frac{5}{7} - (-3\frac{11}{14}) + (-2\frac{1}{4}) = \frac{12}{7} + \frac{53}{14} - \frac{9}{4} = \frac{24}{14} + \frac{53}{14} - \frac{9}{4} = \frac{77}{14} - \frac{9}{4} = \frac{11}{2} - \frac{9}{4} = \frac{22}{4} - \frac{9}{4} = \frac{13}{4} = 3\frac{1}{4} = 3,25\)