Question 875458
No one will answer this post. 
You must post one question at a time. I will do number 6.

6. (8-3i)^2

(8-3i)(8-3i) =

Use foil knowing that i^2 = -1.

64-24i-24i + 9(i^2)

64-48i + 9(-1)

64-48i-9

Answer: 55 - 48i