Ответ:

[tex] \frac{1}{c } = \frac{1}{c1} + \frac{1}{c2} \\ \frac{1}{c} = \frac{1}{0.7 } + \frac{1}{0.7} = \frac{2}{0.7 } \\ c = 0.35 \\ 2) \frac{1}{1.2} = \frac{1}{3} + \frac{1}{c2} \\ \frac{1}{c2} = \frac{1}{1.2} - \frac{1}{3} = 0.83 - 0.33 = 0.5 \\ c = 2 \\ 3) \frac{1}{c1.2} = \frac{1}{1} + \frac{1}{1} = \frac{2}{1} c1.2 = 0.5 \\ \frac{1}{c6.7} = \frac{1}{1} + \frac{1}{1} = \frac{2}{1} c6.7 = 0.5 \\ c3.5 = 1 + 1 = 2 \\ \frac{1}{c3.4.5} = \frac{1}{2} + \frac{1}{1} = \frac{3}{2} c1.2 = 0.66 \\ c1.2.3.4.5 = 0.5 + 0.66 = 1.16 \\ \frac{1}{c1.2.3.4.5.6.7} = \frac{1}{1.16} + \frac{1}{0.5} = 0.86 + 2 = 2.86[/tex]