 In this video, I'm going to talk about identifying the domain and the range of a certain function or of a certain relation. In this case, we're going to give the domain and the range for this relation, okay, relation. Now remember for relation, relation is just a simple, it's a relationship between two different things. So in this case, we're going to have an input and an output. So notice here we have points. We have 10 comma 5, 120 comma 5, so on and so forth. These are all x, y coordinates, which have an input, which is our x coordinate, and then we have an output, which is the y coordinate, okay? So you input the x, usually you put it into an equation. In this case, we don't have an equation, we just have data, we just have numbers, but usually you input the x and then you get out of it a y coordinate. That creates your x, y coordinate, that creates your relationship, your relation. So in this case, what we want to do is we want to find, I want to simply identify the domain and the range of this function, of this relation. The domains are the numbers that we put in, and the range are the numbers that we're going to get out of this. So again, our domain is going to be, the inputs is going to be our x's, okay? So what I'm going to do simply is look at these string of coordinates and I'm going to figure out, hmm, what are the numbers that I'm going to plug in? So in this case, my x's are the numbers I'm going to plug in, so my domain just happens to be all of the x coordinates of this relation. So this would be 100, 120, 140, 160, and 180. These are all of the numbers that I plug in, these are my domain numbers, okay? Also you can also say these are all my inputs, these are all my x coordinates, okay? And on the flip side over here, the range are all the y coordinates of this relation. So in this case, 5 is part of the range, also 5 is part of the range. Now I don't have to, if I have reoccurring ranges, I don't have to list them twice, I can just list them once. So 5 here, I notice I have a 6 here, and then I also have a 12 here at the very end for this y coordinate. So again, I don't have to list out all those ranges, I just have to list them once, I don't have to list them multiple times, it's kind of redundant if I list them multiple times. Anyway, that is the domain and the range of this relation. Again, when you're looking for, when you're looking for the domain and range of a relation or a relationship, whatever you'd like to call it, you always want to look for your inputs, your numbers that you're putting in, and then your outputs, the numbers that you're going to get out of it, and then this is simply just the way to list them. On the other hand, there's a couple of different ways you can list it. This is just one way of doing it, D for domain, and then R for range, kind of just a simple way of listing out the domain and range of this relationship. Okay, that is identifying domain and range, and again, just a real recap domain are the numbers that you plug in, and range are the numbers that you get out of it. Okay, so again, that's identifying domain and range, I hope this video was helpful.