# How do you find the absolute value of 4i?

Sep 1, 2016

$| 4 i | = 4$

#### Explanation:

Absolute value of a complex number $a + i b$ is written as $| a + i b |$ and is equal to $s q t \left({a}^{2} + {b}^{2}\right)$.

Hence $| 4 i |$

= $| 0 + 4 i |$

= $\sqrt{{0}^{2} + {4}^{2}}$

= $\sqrt{0 + 16}$

= $\sqrt{16}$

= $4$