A) (1+2i)(1-4i) = 1 - 4i + 2i - 8i^2= 1 - 2i - 8(-1)= 1 - 2i + 8= 9 - 2i
Б) (3+4i) / (2+3i) = (3+4i) (2-3i) / (2+3i) (2-3i)= 6 - 9i + 8i - 12i^2 / 4 - 9i + 6i + 12i^2= 6 - i - 12(-1) / 4 - 3i + 6i - 12(-1)= 18 - i / 4 + 3i= 18/4 - i/4 + 3/4*i - 9/2= 4.5 - 0.25i + 0.75i - 4.5= 0.5 + 0.5i
A) (1+2i)(1-4i) = 1 - 4i + 2i - 8i^2
= 1 - 2i - 8(-1)
= 1 - 2i + 8
= 9 - 2i
Б) (3+4i) / (2+3i) = (3+4i) (2-3i) / (2+3i) (2-3i)
= 6 - 9i + 8i - 12i^2 / 4 - 9i + 6i + 12i^2
= 6 - i - 12(-1) / 4 - 3i + 6i - 12(-1)
= 18 - i / 4 + 3i
= 18/4 - i/4 + 3/4*i - 9/2
= 4.5 - 0.25i + 0.75i - 4.5
= 0.5 + 0.5i