conjugates are the the same number with an opposite sign in the middle
3 - 6i = 3 + 6i ' the ' mark often denotes a conjugate.. and other things
9 + i = 9 - i '
because complex number represent two different ..(orthogonal ) directions... or at a right angle.. they don't affect each other at all
so to add we just add those part independently
A) (3 - 6i ) + (9 +i )
3+9 + (-6+1)i = 12-5i
B) ( 3 + 6i) + ( 9 - i)
(3+9) + (6+ (-1)) i
12 +5i
C) notice the only difference of the sum of the conjugates is the sign, and so the sum of the conjugates is itself a conjugate too :) this is handy .. especially in elect. engineering :P
