Complex numbers

(1 + i) (2 - i) (3 + i)

( 2 + 2i - 1i - i^2) (3 + i)

(2 + i  - (-1) ) (3 + i)

( 3 + i)  (3 + i)

9 + 3i + 3i  + i^2

9 + 6i  - 1

8 + 6i