## College Algebra 7th Edition

$(-\infty,\ \infty)$
We are given: $g(x)=\sqrt{x^{2}+9}$ The domain of a function consists of all values that $x$ is allowed to have. In this case, we can not take the square root of a negative number: $x^2+9\geq0$ This is true for all values of $x$. Thus the domain is: $(-\infty,\ \infty)$