(3 - 4i)(7 + 5i) = 3 * 7 + 3 * 5i - 7 * 4i - 4i * 5i = 21 + 15i - 21i - 20i² =
= 21 - 6i - 20 * (- 1) = 21 - 6i + 20 = 41 - 6i
41-13i
Объяснение:
(3-4i)(7+5i)
3×7+3×5i-4i×7-4i×5i
25+15i-28i-20i²
21+15i-28i-20×(-1)
21+15i-28i+20
