Answer:
[tex]10i\sqrt{2r}[/tex].
Step-by-step explanation:
[tex]5\sqrt{-8r}[/tex]
= [tex]5\sqrt{-1 * 2 * 2 * 2 * r}[/tex]
= [tex]5i\sqrt{2^2 * 2 * r}[/tex] (i = the square root of -1)
= [tex]5i * 2\sqrt{2 r}[/tex]
= [tex]10i\sqrt{2r}[/tex]
Hope this helps!