Question 674117
This answer is easy. This is just all reals. So, I think the more important thing is to understand what the domain is.

In simplest terms, the domain of a function is what values can x be so that f(x) is defined. Things that might make f(x) undefined are division by 0 or square root of a negative number. Notice that there are no square roots or divisions. By definition, anything of the form x^n + x^n-1... + c is called a polynomial. 

For all polynomials, the domain is defined everywhere. e.g. all reals, (-infinity,infinity)

For all rationals f(x)/g(x), we want g(x) =/ 0.

For all square roots {{{sqrt(f(x))}}} we want {{{f(x) >= 0}}}.
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-Devin