Question

How to find domain for `f(x) = x^2+3`?

Answer 1

The domain is the whole set `\mathbb{R}`.

Explanation:

The domain of a function is the set of value you can give as input to the function. Now, your function takes a number `x`, squares it (`x^2`), and then adds `3`: (`x^2+3`).

The question is: is there any number which can't be squared? And the answer is no: we can square any real number, since it is always a legit operation. Needless to say, we can also always add `3` to any number. So, there are no numbers to exclude from the domain.