а) $$\frac{1}{1 - i} = \frac{1}{1 - i} * \frac{1 + i}{1 + i} = \frac{1 + i}{1 - i^2} = \frac{1 + i}{1 + 1} = \frac{1 + i}{2} = \frac{1}{2} + \frac{1}{2}i$$
б) $$\frac{3 - 5i}{2 - 4i} = \frac{3 - 5i}{2 - 4i} * \frac{2 + 4i}{2 + 4i} = \frac{(3 - 5i)(2 + 4i)}{(2 - 4i)(2 + 4i)} = \frac{6 + 12i - 10i - 20i^2}{4 - 16i^2} = \frac{6 + 2i + 20}{4 + 16} = \frac{26 + 2i}{20} = \frac{13 + i}{10} = \frac{13}{10} + \frac{1}{10}i$$
**Ответы:**
* **a) $$\frac{1}{2} + \frac{1}{2}i$$**
* **б) $$\frac{13}{10} + \frac{1}{10}i$$**