How do you find abs( -2+i )?

May 3, 2016

$| - 2 + i | = \sqrt{5}$

Explanation:

Given a complex number $a + b i$, that number's modulus, denoted $| a + b i |$, is given by

$| a + b i | = \sqrt{{a}^{2} + {b}^{2}}$

In this case, that gives us

$| - 2 + i | = \sqrt{{\left(- 2\right)}^{2} + {1}^{2}} = \sqrt{4 + 1} = \sqrt{5}$