Help with subtracting radicals?

Question

This is the problem:

0.5√200 - √-32 = ?

So far I broke it down to: 5√2 - 4i√2

Is this the best answer or does it need to be simplified even further?

Answer 1

= 0.5 x 10 x √2 - √ 32 i²
= 5.√2 - 4.√2.i
= √2.( 5 - 4 i )

Answer 2

You mean (5-4i)√2 ? not sure which is the "best answer - it depends on what you're going to do with it. I don't see any obvious way to simplify it any more - unless you convert it to its trignometric form, you know, e^(iΘ)...which I would assume you haven't been shown yet (and probably never will be).