Changes

:Any nonnegative real number x has a unique nonnegative square root r; this is called the ''principal square root'' and is written r = x^1/2 or r = √x For example, the principal square root of 9 is +3, while the other square root of 9 is -3. In common usage, unless otherwise specified, "the" square root is generally taken to mean the principal square root.

:Any nonnegative real number x has a unique nonnegative square root r; this is called the ''principal square root'' and is written r = x^1/2 or r = √x For example, the principal square root of 9 is +3, while the other square root of 9 is -3. In common usage, unless otherwise specified, "the" square root is generally taken to mean the principal square root.

So this source seems to be saying that the ''phrase" square root includes both values, i.e. there are two "square roots," but that the notation x^1/2 and r = √x refer ''only'' to the principal or positive-valued square root. Thus, according to this source, one could write:

So this source seems to be saying that the ''phrase'' square root includes both values, i.e. there are two "square roots," but that the mathematical notation using the symbols x^1/2 and r = √x refer ''only'' to the principal or positive-valued square root. Thus, according to this source, one could write:

:The two square roots of 9 are ±3.

:The two square roots of 9 are ±3.

They don't actually say this but they do use parallel language later, when they say:

They don't actually say this but they do use parallel language later, when they say: