Question

http://prntscr.com/3lu6kh

Answer 1

The answer choices are tricky: You have 8i, which seems possibly correct, but you also have -8i which also is a square root of -64. But then you have choice D, that is \[i\sqrt{64}\]which includes both 8i and -8i since sqrt(64) can bd 8 or -8. So D is the correct answer!