Graphs of Two Variables - Video Tutorials & Practice Problems
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Plotting Points on a Graph
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Hey guys, I know a lot of you haven't seen graphs for a while. So I'm including this review to refresh you on a lot of those concepts and if you feel a little more comfortable with the math, I still suggest watching it. You might get some value out of it. The first thing we've got here is our two variable graph on the left. Okay. We're going to learn what the key parts of the graph are and how to plot points on the graph in this video. So first we're gonna label what are called the axis of the graph. So here on the bottom, what I've just highlighted in red, this is called the X axis for our X values and on the other axis going up we have the y axis. Cool. Generally we're gonna have numbers or values that tell us how much each jump in the graph is and for now we're just gonna go 1234567. Right? And usually when I give you graphs in this class, um you're going to not have to do this right? I'll have done it already. I just figured the first time we do it together, just so you get a feel for it. So here on the right, I have what's labeled a demand schedule and it's got some prices and some quantities, right? So at certain prices there's gonna be certain quantities that are demanded and later in the course we're gonna dive into these topics more. But for now what I wanna do is get these points onto the graph. Right? So the first thing we have to do is we're gonna label one of our axes as the as the price and one of our axes is the quantity in economics, we tend to label the Y axis as price and the X. Axis as quantity. This is how they've been doing it. This is just the convention in economics that's been around for a long time. So this is how we will do it as well, Price on the vertical axis and quantity on the horizontal axis. So let's go ahead and get these pairs what we call pairs of numbers and we're gonna plot them on the graph. So let's start with the first one which I'll call, let's label them all A B C D. E. Just so we know which one we're talking about when we're on the graph. So let's start with 61 a price of six and one demanded. So I'm gonna go to my price axis and find six right up here and I'm gonna start going out, right and then when I go to the quantity I'm gonna find one And I'm gonna go up from there and I'm gonna find the point where these two cross with each other. Right? So right here that's gonna end up being the .6 for price and one for quantity right there. I'm gonna erase some of those extra. Cool. So that's gonna be point a right there. Let's go ahead, I'm not gonna change colors because I'm I'm not gonna have five different colors for this right now I don't think we'll need it but let's go ahead and plot the rest of these. So actually for this one I'll use blue and then I'll rotate back to read just just to keep it a little consistent. So um here we have a price of five and a quantity of two. So we'll find five on our price access to on our quantity axis and we'll find the place where they mix or where they meet and that's gonna be right there. Point B. Let's go back to red and we'll do the same thing for C. So now we've got a price of four and a quantity of three right and that'll be point. See right there. Now point D. I'm gonna do in blue and that's got a price of three and a quantity of four. So you can see these are kind of the places where you can get mixed up which way you know which axes do I put the three, which one do I put the four? So you just have to make sure that you're on the right access when you start counting. So that'll be point D right there and let's finish it up with E. At a price of two and a quantity of five right there. That's point B. Right there. Cool. So that's how we plot stuff onto the graph I guess I'll put this as a blue B. And a blue D. Just to match what we've got going there. Cool. Alright, let's move on to the next example.