# How do you find the product of each complex number –2i and its conjugate?

##### 1 Answer
Feb 23, 2017

Product of complex number $- 2 i$ and its conjugate is $4$.

#### Explanation:

Complex conjugate of a complex number $a + i b$ is $a - i b$ and that of $a - i b$ is $a + i b$.

Hence, as $- 2 i$ can be written as $0 - 2 i$,

its complex conjugate is $0 + 2 i$ or $2 i$

Hence, their product is

$- 2 i \times 2 i$

= $- 4 {i}^{2}$

= $- 4 \times - 1$

= $4$