Question

(2+3i).(2-5i)
(2-5i). (4-2i)
(4-2i).(-8-7i)

Answer 1

(2+3i).(2-5i)= 4-10i+6i-15i²=4-4i+15=19-4i

(2-5i).(4-2i)= 8-4i-20i+10i²= 8-24i-10=-2-24i ou 2+24i

(4-2i).(-8-7i)= -32-28i+16i+14i²= -32-12i-14=-46-12i ou 46+12i