- In this example, we want to graph x equals 2. So when we look at x equals 2, we just see we have one variable. And one way to look at this is to actually make a table. So for example, we can make an x, y table like this. And sometimes, students get a little confused, so this kind of helps to straighten things out for them. 

So for example, say, for example, if y is 0, x is going to be 2. Say y is 1. x is going to be 2. Say y is 2. x is going to be 2. Say y is 3. x is 2. See, no matter what y is, x is always fixed at 2. So if we plot these points, you can see 2 comma 0 is here, 2 comma 1, 2 comma 2, 2 comma 3. And you can see we're actually getting a vertical line. 

OK? So what you can remember, if you want to memorize this, is that you can say, well, x equals lines. These are vertical lines. These have an undefined slope. And again, if you forget, just go ahead and make a table. 

Our next example, we want to graph y equals 3. Now, same thing. If we want to make that table, we can see that no matter what x is-- 1, 2, 3, 4-- y is always fixed at 3. So if we plot these points, you can see 1, 3, 2, 3, 3, 3, 4, 3. You can see we're actually getting a horizontal line. 

Now, this might make a little bit more sense if you've learned about the slope intercept form of the line, the y equals mx plus b form of the line, because here, you can see that there isn't an x term. That means that this is really like 0 x, y equals 0 x plus 3. And so what we can say our y-intercept is 3, and then we're rising 0. We're running 1. Rising 0, running 1. But again, you can just memorize that y equals lines are these horizontal lines. That's probably the quickest way to do it. But again, if you forget, you can use a table or put it into the slope intercept form.