Hello we're going to look at Cartesian coordinate systems. Cartesian coordinate system is made-up of a horizontal line and a vertical line. The horizontal line is called the X axis and it tells us how far right or left to go. The vertical line is called the Y axis and it's going to tell us how far up or down to go. The two lines intersected a point. The point is referred to as the origin, and because we haven't gone left or right any, it's going to be coordinate zero and we haven't gone up or down any, it's going to also be zero. So the first coordinate is going to be our X, the 2nd is going to be our Y, the 1st is referred to as the abscissa, and the 2nd is the ordinate. The abscissa once again tells us left or right and the ordinate tells us up or down. Now these two lines divide the graph into four sections. The four sections are referred to as quadrants and the quadrants get counted as the upper right going counterclockwise. So quadrant 1, quadrant 2, quadrant 3, and quadrant 4. Once again those are referred to as quadrants. The next thing we need to explore is does a point fit a line? Let's say we have any old line Y equal to X -, 1 and some given .30. To determine if this point is on the line or not, we're going to stick 3IN for the X and 0 in for the Y and determine if it's a true statement. So does 0 equal 2 * 3 - 1? Well, 0 = 6 - 1 zero equal 5. No, it's not true. So the point is not on the line. Let's look at a different point. If we look at the point zero -1, now we're going to put zero in for the Y. Sorry, zero in for the X and -1 in for the Y. Does -1 equal 2 * 0 zero -1? And this answer is yes. So the point is on the line. The other topic we need to refer to for this lesson is whether or how to graph equation. If we're given the equation Y equal to X -, 3, we're going to use what's called AT chart. And the T chart just means we're going to stick in X values and Y values. If we stick in X values we're going to usually use a couple positive zero and a couple negative. So when I put 2IN for my XI want to find my Y value Y 2 * 2 - 3. So 4 - 3 would give me AY value of one. That's an ordered pair. When X IS2Y is 1, the next one we're going to stick one in for our X 2 * 1 - 3. So 2 -, 3 is -1. This is a new ordered pair when X IS1Y is -1. Following the same procedure, we're going to stick zero in for our X and we're going to get AY value of -3 once again, a new .0 negative 3 when Y is -1. When sorry, when X is -1 negative 2 -, 3 is -5 once again another new point, X is -1, Y is -5. And finally, for this example, we're going to stick in -2 for our X and we're going to get -7 out for our Y. Once again, another point. So now we can actually graph these points. If we graph these points, we're going to have two, one positive 2/1. So to the right two, up one, to the right, one down one none right or left and down 3 left one, down 5, left two, down seven. When we connect that line, we have a graph. Thank you very much.