# How do you find the complex conjugate of -5i?

Jan 6, 2016

Reverse the sign of the imaginary part to find the conjugate to be

$5 i$

#### Explanation:

The complex conjugate of a complex number $a + b i$ is $a - b i$.
If we put our number into the $a + b i$ form, we have

$- 5 i = 0 - 5 i = 0 + \left(- 5\right) i$

Then, the complex conjugate of $- 5 i$ is

$0 - \left(- 5\right) i = 5 i$