Coordinate plane relationships

We're told Jazella plots the ordered pair (4, 3) on a coordinate grid by moving four units to the right and three units down from the origin. Which statement is true? So pause this video and have a go at this before we do this together.

All right, now before I even look at the choices, let's just think about how we would approach it if we had to graph (4, 3). So let me draw some coordinate axes here. So that is my y-axis, this right over here is my origin, and that is my x-axis.

If I had to graph (4, 3), the first coordinate is the x-coordinate, so it says how much to the right do we move in the x-direction. So I'm moving four from the origin to the right. Let's say that that is four right over there. Maybe that's one, two, three, and then four. So I'd move four to the right, and then the y-coordinate right over here says how much do I move up.

So then I would move three up to get right over here. So maybe this is three right over here. This would be one, two, and three to go here. So I'd go four to the right and then three up.

Now, it said that Jazella moved four units to the right, that's right, and three units down from the origin. So Jazella did something like this: four to the right and then three units down, and that does not make sense.

So let's see. A says Jazella did both of them correctly. That's not right. Jazella plotted the x-coordinate incorrectly and the y-coordinate correctly? No, it's the other way around. Jazella got the x-coordinate right; they went to the right but then should have gone up instead of down, so this one isn't right.

Jazella plotted both the x and the y-coordinate incorrectly? That's not right either. Jazella, she got the y... Sorry, she got the four part right; she got the x-coordinate correct. Then, through the process of elimination, let's read this: Jazella plotted the x-coordinate correctly. That's right; she did the four to the right and the y-coordinate incorrectly. Correct! She went down when she should have gone up.

So I like this choice. Let's do another example. So here we are told that Lucia tries to graph the point (8, 2) on a coordinate grid. She starts at the origin, moves eight units up, and then moves two units to the right.

So let me just think about how I would do that. So if that right over there is my x-axis, this is my y-axis, that's my origin right over there. Then, let's see, if I had to deal with (8, 2), that first coordinate right over there, the eight is the x-coordinate; it tells you how much to move to the right.

So I would move eight to the right. Let's say right over here, eight to the right. And then the second coordinate is the y; it tells you how much to move up, and then I would move two up. So I'd get to this point right over here. So this is eight to the right and then two up.

Lucia went eight up and two to the right, so it looks like Lucia actually maybe confused the x and the y coordinates. So let's see which mistake did Lucia make?

Lucia moved two units right instead of two units down? No, that makes... it should have been moved two units to the right instead of two units up. I'll rule that one out.

Lucia moved eight units up instead of eight units to the right? That one looks right, so I like this one, I will save that one.

Lucia moved two units to the right instead of two units to the left? No, this two right over here isn't talking about right or left; it's talking about how many units up, so rule that one out.

Lucia moved eight units up instead of eight units? No, it should have been eight units to the right, like we see in choice B, and we're done.