I am going on my own through a chapter on functions and here is something that puzzled me in the definition:(adsbygoogle = window.adsbygoogle || []).push({});

Each element in the domain is paired with just one element in the range.

I guess my calculus knowledge interferes, but what about function like f(x) = sqrt(x). It has two roots: + and -. How does set theory account for that? Or is sqrt(x) not a function in set-theoretic terms

Although f(x) = x^2 fits the definition of the function.

Could someone please explain?

Thanks in advance.

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# Chapter on functions

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