can you put a negative sign in a square root sign

Expanding on Dragonslayer's answer, yes, it is possible to have a negative square root, such as  $${\mathtt{\,-\,}}{\sqrt{{\mathtt{4}}}} = -{\mathtt{2}}$$

However, the square root of a negative number does not exist in the real number system, so there is this term called  $${i}$$   to express  $${\sqrt{-{\mathtt{1}}}}$$ . Square roots of negative numbers are expressed in terms of  $${i}$$  

Like this?

$$-\sqrt$$

Yes. It is possible.

√-1 = non real number or doesn't exist

Yes. Thank you kitty<3. I tried to get to that point, but I didn't know how to explain it.