Removing the negative inside of a square root?

[yo4561]

Hi MP,

if you have squareroot(-x), why are you allowed to make this negative squareroot(x)? How come we can remove the negative from inside the square root? Does this only work for square roots though (e.g., I would imagine for cube roots, that this principle does not apply).

Thank you

[esledge]

Where did you see this move? Technically, you can only remove something that is a perfect square from under the root and move its root to the outside. Example:

sqrt(50) = sqrt(25*2) = 5*sqrt(2)

Since -1 is not the square of any real number, you can't just move the sign out.