If I go by the same logic then Sqrt ((-2).(-2)) = 2 and cannot be equal to -2. I don't really see the reason behind that. Why couldn't the root be -2?
The official rule is that the sqrt(x^2) = abs(x) for every real number x
Negatives inside sqrts mean imaginary numbers. Not on the test.
Edit: Hopefully I haven't added to the confusion - it's late & my brain is fried. If you're lost, check out basic imaginary number stuff. IE, sqrt(-1) = i. ... Again, NOT on the test.