Denominators are not allowed to be zero, so
domain is all values of x except -4 and -6.
For additional information on domain and range, especially if you want an explanation that is easier to understand than traditional textbooks, see my website by clicking on my tutor name "rapaljer" anywhere in algebra.com. Then look for the "MATH IN LIVING COLOR" page, click on "College Algebra", "Chapter 2", "Section 2.07."