Polynomial functions and rational functions

The purpose of this discussion is to find out why some rational functions are not defined for a certain real numbers . Consider the rational function

f(x)=X2+5x+6 / X2-4x+3

Instruction:

1. Find the domain of f(x) in set builder notation
2. Find the domain of f(x) in interval notation.
3. Evaluate the function at x=1, and x=3 and discuss your findings
4. Comment to at least 2 students post.