81 A Find the following product Simplify your answer complet

8.1

Find the following product. (Simplify your answer completely.) (4 3)(55 i)

A. (4+3i)(5-i) = 20-4i +15i -3i^2= 20+11i +3 =23+11i

B (4+2i)(4-2i)= 16 -8i+8i-4i^2 = 16+4=20

C.(3+4i)/(3-4i)

multiplying both top and bottom by 3+4i

(3+4i)(3+4i)/(3-4i)(3+4i)= (9+12i+12i+16i^2)/(9+12i-12i-16i^2)= (9+24i-16)/(9+16)= -7+24i/25