To rewrite each square root, factor each number and use one of the properties of roots, this way:
[tex]\sqrt[]{-4}=\sqrt[]{4\cdot-1}=\sqrt[]{4}\cdot\sqrt[]{-1}=2i[/tex][tex]\sqrt[]{-5}=\sqrt[]{5\cdot-1}=\sqrt[]{5}\cdot\sqrt[]{-1}=i\sqrt[]{5}[/tex]The blanks must be filled in with 2i and i sqrt(5) respectively.
