# How do you find the domain in interval notation for f(x)=(x+6)/(x^2+5) ?

The domain of a function is all the values that $x$ can take (in order to avoid having something like $\frac{a}{0}$, which isn't defined).
In your case, ${x}^{2} + 5 > 0$ with $x \in \mathbb{R}$; therefore, there is no way you could have a division by zero.
Thus, the domain $D = \mathbb{R}$ or, in interval notation, D = ]-oo;+oo[.