The complex conjugate of something is essentially just taking the opposite sign of the imaginary part. The following are complex conjugates:
a + bi
a - bi
In this case the complex conjugate of 9 - 4i is 9 + 4i
Now we must add them together like so:
(9 - 4i) + (9 + 4i)
9 - 4i + 9 + 4i
^^^Combine like terms
(9 + 9) + (-4i + 4i)
18 + 0
18
As you can see when you add complex conjugates your answer will be a real number
Hope this helped!
~Just a girl in love with Shawn Mendes
