We have this equation for the slope is: y=mx+b which m is the slope and b is the y-intercept, so we have y=20-15x or y=-15x+20, and we already know that the slope is -15 and y-intercept is 20. As a result, the student's error is that he thinks that 20 is the slope because it is the first number. Hope it help!
B and C make sense to me.
Given: Points (-9, 6) and (-3, 9)
Find: The slope of the line that goes through those two points
Solution: In order to find the slope of the line that goes through the points that were provided we have to use the slope formula. This formula subtracts the y-coordinates from each other and also the x-coordinates from each other to determine the rise/run which would give us the rate of change.
<u>Plug in the values</u>
<u>Simplify the expression</u>
Therefore, looking at the given options we can see that the best fitting one would be option A, 1/2.
To get the coordinates of C we shall proceed as follows:
AB:BC=1:4
B-A=[(-3--7),(-5--8)]=(4,3)
4(4,3)=(16,12)
thus the coordinates of C will be:
(16-3,-5+12)
=(13,7)