Ответ:

[tex] \frac{1}{r2.3} = \frac{1}{r2} + \frac{1}{r3} \\ \frac{1}{r1.2} = \frac{1}{6} + \frac{1}{20} = \frac{120}{120} \\ r2.3 = 1om \\ r1.2.3 = r1 + r2.3 \\ r1.2.3 =6+ 1 = 7om \\ u = r \times i \\ u = 7 \times 0.2 = 1.4v [/tex]