Question

How do you write the complex conjugate of the complex number `5i`?

Answer 1

`-5i`

Explanation:

For a complex number `z=(a+bi) {a,b} in RR`, the complex number `z'=(a-bi)` is said to be its "complex conjugate".

[Note that the product of a conjugate pair is:
`zxxz'=a^2+b^2` which is real]

In this example `z = (0+5i)`
So, `a=0` and `b=5` in this case

`:. z' = (0-5i)` which can be written as simply `-5i`