On every notable standardized math test in the US, and on any commonly used calculator, a square root is non-negative. Another example: http://www.wolframalpha.

On every notable standardized math test in the US, and on any commonly used calculator, a square root is non-negative. Another example: http://www.wolframalpha.com/input/?i=sqrt(x) http://www.wolframalpha.com/input/?i=sqrt(x)