Video1:Subtract 2 points to find SLOPE

This example says that line F passes through points 8.7 and in 5 11, line G passes through points, three three, and 7 6 are F and G parallel or perpendicular. When given two points, 8 7 and 5 11 in order to find the slope, you're going to have to subtract. So 8 7 and 5 11. We are going to subtract to find the slope. So we have 8 7, and then underneath it please put 5 11. These are my X numbers. These are my wide numbers. Please circle. Your 7 and your 11. Please circle them. In order to find slope, you have to subtract your Y's at the top. And your X is at the bottom. You have to put the Y's at the top. Slope is rise over run. Because the Y axis is the axis that rises up and down. Rise over run. The X axis is the one that runs right or left. So my two Y numbers, I have 7 -11, and then I have 8 -5. Please make sure that you subtract in the same direction. 7, -11, 8 -5. So don't put 7 -11 and 5 -8. It matters what direction you're going in. 7 -11 and 8 -5. So this 7, there's an imaginary plus sign in front of the 7, which means I have $7 in my pocket. The negative in front of that 11 means that I have to give you I have to give you. $11. If I only have 7, but I have to give you 11, do I have enough to give you? I don't. So that means that it's going to be a negative answer. 7, 8, 9, ten, 11. I still owe you $4. The 8, there's an imaginary plus sign in front of the 8. That means I have $8 in my pocket. The negative sign in front of the 5 means I have to give you. $5. If I have 8 in my pocket, I have to give you 5. I have enough to give you. That means I have $3 left in my pocket. So we have a negative four over three. That is a slope of line F. So now we're finding the slope of the next line G, which is three three. And 7 6. These are my two X numbers because at first, there's a Mark two Y numbers because they're less. I'm going to circle them. That means that these are the numbers that I'm going to subtract together. So now I have three -6. And then three -7. There's an imaginary plus sign here and a measurement plus sign here. This means I have $3. This means I have to give you. $6. I don't have enough money to give you. Which means that my answer is going to be negative. Negative three. If I have three, I have to give you 7. I don't have enough to give you. This means that my answer here is going to be a negative $4. I have three, I have to give you 7. I still owe you $4. When you have your two negative signs. Remember the fraction line really means division. When you multiply or divide, that is when you use your peace sign. Which are plus your minus in your minus. I see a negative here. I'm going to scratch that out. I see negative here. I'm going to scratch that out. So two negatives divided by each other means that this is actually a positive three over four. So your slope. For line G is actually a positive three over four. Your slope for line F is a negative four over three. Because the numbers are flipped, the fours at the top, the threes at the bottom, and the signs are different. There is a plus sign here, because two negatives divided equals a positive. Because they have different signs and the numbers are flipped. That means that these two lines are perpendicular. So I'm going to go back up here. And I'm going to Mark perpendicular. And that is correct.