Question

In a answered math the problem $\sqrt{-2}$ plus $\sqrt{-18}$ was $4\sqrt{2i}$ as it was rewritten as $\sqrt{2i} + \sqrt{18i}$. Why can $\sqrt{-2}$ be written as$\sqrt{2i}$

Answer 1

Ok so basically this is this and that is that !

Answer 2

$\text{The imaginary unit,}~ i = \sqrt{-1}\\\\\sqrt{-2} ~ \text{can be written as.}\\\\\sqrt{-2}\\\\=\sqrt{-1 \cdot 2}\\\\=\sqrt{-1} \sqrt{2}\\\\=i\sqrt 2\\\\=\sqrt 2 i$