Hi, just finished my first calculus lesson in university. I am just wondering how does one express the range in university notation? I have this question, express the range of the function of y = x^(-1). I have no idea how to right it on the university level. I would write it as yeR, y =/= 0. How would I write it in university level because the teacher claims not all numbers are going to be real that is why you use the notation of "D".

Also, how do I generalize the domain of y=tan(x) in university level? I ask this because I have no idea how to show the asymptotes mathematically.