Note that if [tex]i^2=-1[/tex] than [tex]i=\sqrt{-1}[/tex],
Also note that [tex]\sqrt{ab}=\sqrt{a}\sqrt{b}[/tex]
So we have,
[tex]\sqrt{-49}=\sqrt{-1}\sqrt{49}=\boxed{7i}[/tex]
and,
[tex]\sqrt{-4}=\sqrt{-1}\sqrt{4}=\boxed{2i}[/tex]
Hope this helps.
r3t40
