Hey there!
In order to find the additive inverse of any number, regardless if it is real or not, you can simply multiply the number by -1 or negate it.
This should look like this:
-(6-3i)
=-6+3i
Therefore, the additive inverse of 6-3i is -6+3i.
**Note: Keep in mind, when the additive inverse of a number is added to the number, the number equals 0:
(6-3i)+(-6+3i)=0
Hope this helps and have a marvelous day! :)
