None of them is correct, When you do
[tex]x^{2} =-4[/tex]
It become this:
[tex]\sqrt{x}[/tex]²[tex]=\sqrt{-4}[/tex]
you cancel the ² with [tex]\sqrt{}[/tex] or square root. However this cause the problem since -4 is negative and there isn't just one answer because of square root.
i = [tex]\sqrt{-1}[/tex]
[tex]x= i\sqrt{4}[/tex] or [tex]x=-i\sqrt{4}[/tex]
Square root the 4, the final answer is
[tex]x=2i[/tex] or [tex]x=-2i[/tex]
