We have
f(x) = [x - (-3+i) ] [ x - (-3-i)] =
[x + 3 - i] [ x + 3 + i ] =
x + 3 - i
x + 3 + i
-----------------
ix + 3i - i^2
3x + 9 -3i
x^2 + 3x -ix
----------------------------------------
x^2 + 6x + 9 -i^2 = [i^2 = -1 ]
x^2 + 6x + 9 - (-1) =
f(x) =x^2 + 6x + 10
