Answer:
x<-3 or -3<x<-1 or x>-1
Explanation:
Domain - The domain of a function is the set of all possible inputs for the function. For example, the domain of f(x)=x² is all real numbers, and the domain of g(x)=1/x is all real numbers except for x=0.
\mathrm{Domain\:of\:}\:\frac{1}{x^2+4x+3}\::\quad \begin{bmatrix}\mathrm{Solution:}\:&\:x<-3\quad \mathrm{or}\quad \:-3<x<-1\quad \mathrm{or}\quad \:x>-1\:\\ \:\mathrm{Interval\:Notation:}&\:\left(-\infty \:,\:-3\right)\cup \left(-3,\:-1\right)\cup \left(-1,\:\infty \:\right)\end{bmatrix}