# How do you find abs( -18/7 + sqrt5/7 i )?

$| - \frac{18}{7} + \frac{\sqrt{5}}{7} i | = \sqrt{\frac{324}{49} + \frac{5}{49}} = \sqrt{\frac{47}{7}}$
For general complex number $z = x + i y$ in rectangular form, the modulus is given by $| z | = \sqrt{{x}^{2} + {y}^{2}}$.
$| - \frac{18}{7} + \frac{\sqrt{5}}{7} i | = \sqrt{\frac{324}{49} + \frac{5}{49}} = \sqrt{\frac{47}{7}}$