SOLUTION: Find the slope and the y intercept (8,6)(7,7) I have no idea where to even begin

Algebra ->  Graphs -> SOLUTION: Find the slope and the y intercept (8,6)(7,7) I have no idea where to even begin      Log On


   



Question 87775: Find the slope and the y intercept (8,6)(7,7) I have no idea where to even begin
Answer by jim_thompson5910(35256) About Me  (Show Source):
You can put this solution on YOUR website!
Solved by pluggable solver: Finding the Equation of a Line
First lets find the slope through the points (8,6) and (7,7)


m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29 Start with the slope formula (note: (x%5B1%5D,y%5B1%5D) is the first point (8,6) and (x%5B2%5D,y%5B2%5D) is the second point (7,7))


m=%287-6%29%2F%287-8%29 Plug in y%5B2%5D=7,y%5B1%5D=6,x%5B2%5D=7,x%5B1%5D=8 (these are the coordinates of given points)


m=+1%2F-1 Subtract the terms in the numerator 7-6 to get 1. Subtract the terms in the denominator 7-8 to get -1




m=-1 Reduce



So the slope is

m=-1





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Now let's use the point-slope formula to find the equation of the line:




------Point-Slope Formula------
y-y%5B1%5D=m%28x-x%5B1%5D%29 where m is the slope, and (x%5B1%5D,y%5B1%5D) is one of the given points


So lets use the Point-Slope Formula to find the equation of the line


y-6=%28-1%29%28x-8%29 Plug in m=-1, x%5B1%5D=8, and y%5B1%5D=6 (these values are given)



y-6=-x%2B%28-1%29%28-8%29 Distribute -1


y-6=-x%2B8 Multiply -1 and -8 to get 8%2F1. Now reduce 8%2F1 to get 8

y=-x%2B8%2B6 Add 6 to both sides to isolate y


y=-x%2B14 Combine like terms 8 and 6 to get 14

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Answer:



So the equation of the line which goes through the points (8,6) and (7,7) is:y=-x%2B14


The equation is now in y=mx%2Bb form (which is slope-intercept form) where the slope is m=-1 and the y-intercept is b=14


Notice if we graph the equation y=-x%2B14 and plot the points (8,6) and (7,7), we get this: (note: if you need help with graphing, check out this solver)


Graph of y=-x%2B14 through the points (8,6) and (7,7)


Notice how the two points lie on the line. This graphically verifies our answer.