Most people are taught that there are two values for the square root. It was only in later math courses (e.g. precalculus) that they reserved the square root symbol exclusively for the positive square root.

That is not what people are taught. If that were true, the numerator in the quadratic equation would be "-b + √(b² - 4ac)", not "-b ± √(b² - 4ac)".

Your statement assumes the educational system values consistency, which is a clearly false assumption.

Textbooks aren't that bad. Here's what Pearson's Algebra 1 says when introducing the novel concept of the radical sign:

> The radical symbol √ indicates a nonnegative square root, also called a principal square root.

I quoted that one because it's available on libgen ( http://library.lol/main/BE522034F8D3680B248162CD2C35D455 , page 16), but obviously every basic algebra textbook covers this. The symbol is never discussed -- or used -- in any other terms than that it uniquely refers to a positive square root.

Your evidence is consistent with my claims. Or rather: I never claimed there aren't textbooks that define it as the positive square root.

All textbooks define it that way. There is no other definition available for that symbol.