00:02
Okay, we need to find the slope of a line that passes through these two points.
00:08
Let's go ahead and label them x1, y1 and x2, y2 because our formula for slope is y2 minus y1 over x2 minus x1.
00:26
So let's plug in the values from our points.
00:30
Y2 is 1 eighth, y1 is 7, x2 is negative 15, x1 is negative 10.
00:45
Okay, 1 eighth minus 7, we've got to evaluate that.
00:50
So let's put 7 in terms of eighths.
00:55
So it's going to be 7 times 8 over 8, and 7 times 8 is 56.
01:05
So let me just replace that with 56.
01:15
And 1 minus 56 is negative 55 over 8, and that's divided by negative 15 minus negative 10, which is the same as negative 15 plus positive 10.
01:32
So that is negative 5.
01:37
So then we can combine our composite fraction here, and we would have negative 55 over 8 times 1 over negative 5.
01:54
So that's going to be, we could cross -cancel the 55 and the 5, because 55 divided by 5 is 11, so we'd end up with negative 11 over 8.
02:17
No, positive, because we had a negative divided by a negative.
02:24
Negative 55 divided by negative 5 is positive 11.
02:28
So 11 over 8 is our slope for that one.
02:32
That was number 1.
02:37
Number 2, the two points were 7, negative 2, and 7, negative 1, 6.
02:53
So same formula, y2 minus y1 over x2 minus x1.
02:57
Y2 is negative 1, 6, because that's the second y -coordinate.
03:05
Y1 is negative 2, so we're going to subtract negative 2.
03:12
X2 is 7, and x1 is also 7.
03:18
So i could save myself some time and notice that the denominator is 0.
03:29
So it doesn't really matter what we get for the top.
03:36
I'll just call it delta y.
03:38
I don't need to bother working that out, because when i divide by 0, i know that my slope is undefined, because this would be a vertical line.
03:55
Ok, let's move on to number 3.
04:01
3 was negative 1, negative 2, and negative 4, negative 6.
04:15
Ok, y2, second y -coordinate, negative 6.
04:20
Y1, first y -coordinate, negative 2, minus negative 2.
04:26
X2, second x -coordinate, minus first x -coordinate, x1, negative 1...