4.319 Вычислите: a) б)

**Решение:** **a)** Начнем с центра: \(\frac{1}{7}\) 1) \(\frac{1}{7} + 1 = \frac{1}{7} + \frac{7}{7} = \frac{8}{7} = 1\frac{1}{7}\) 2) \(\frac{1}{7} + 2 = \frac{1}{7} + \frac{14}{7} = \frac{15}{7} = 2\frac{1}{7}\) 3) \(\frac{1}{7} - \frac{1}{7} = 0\) 4) \(\frac{1}{7} + \frac{5}{7} = \frac{6}{7}\) 5) \(\frac{1}{7} + \frac{6}{21} = \frac{1}{7} + \frac{2}{7} = \frac{3}{7}\) 6) \(\frac{1}{7} + \frac{1}{9} = \frac{9}{63} + \frac{7}{63} = \frac{16}{63}\) **б)** Начнем с центра: \(\frac{1}{12}\) 1) \(\frac{1}{12} + (-1) = \frac{1}{12} - \frac{12}{12} = -\frac{11}{12}\) 2) \(\frac{1}{12} + \frac{5}{12} = \frac{6}{12} = \frac{1}{2}\) 3) \(\frac{1}{12} + (-\frac{1}{4}) = \(\frac{1}{12} - \frac{3}{12} = -\frac{2}{12} = -\frac{1}{6}\) 4) \(\frac{1}{12} + (-\frac{1}{6}) = \(\frac{1}{12} - \frac{2}{12} = -\frac{1}{12}\) 5) \(\frac{1}{12} + (-\frac{7}{12}) = -\frac{6}{12} = -\frac{1}{2}\) 6) \(\frac{1}{12} + \frac{1}{4} = \(\frac{1}{12} + \frac{3}{12} = \frac{4}{12} = \frac{1}{3}\)