Fuzzy bizz

.In jacksons class i have a little struggle with finding the domain and range of a rational. I do all the homework but sometimes it just seems like it makes no sense. I partially got it and the basic knowledge of it but everytime i think i was right to found out again ha just kidding i was actually wrong. And that is a little fuzzy part in functions for me and hopefull i can solve it out before the test come and is too late for me. It probably is not that hard im just making it way more complicated then it really has to be