# How do you find abs( -3+4i)?

Mar 30, 2016

$| - 3 + 4 i | = \sqrt{{\left(- 3\right)}^{2} + {4}^{2}} = 5$

#### Explanation:

Let $z = x + i y$ be any complex number in rectangular form.

Then its modulus is given by $| z | = \sqrt{{x}^{2} + {y}^{2}}$.

So in this case we get

$| - 3 + 4 i | = \sqrt{{\left(- 3\right)}^{2} + {4}^{2}} = \sqrt{25} = 5$