Talk:square root

The (square) root of a number is always positive. However, the equation x² = 4 has two solutions, 2 and -2, or stated differently, √4 and -√4 \Mike

This is not quite the usage I learned when I got my math degree.

There are a couple of things going on. A number is a square root of another number iff its square is the number in question. That is, -2 and 2 are both square roots of 4.

On the other hand, the square root function, being a function, must choose one or the other possibility, so by convention it is defined to be non-negative. That is, the result of applying the square root function to a non-negative number is another non-negative number.

However, this is a fine point. In general usage, even among mathemeticians, square root means positive square root. But the usages a square root and the positive square root are used when there may be ambiguity.

I'm not going to update the definition right now pending wider consensus, particularly since Wikipedia takes the "postitive" view. -dmh 17:58, 19 Apr 2004 (UTC)~

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