SOLUTION: What is the equation of the line that contains the points with (x,y) coordinates (-3, 7) and (5, -1)?

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Question 85245: What is the equation of the line that contains the points with (x,y) coordinates (-3, 7) and (5, -1)?
Found 2 solutions by jim_thompson5910, chitra:
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 (-3,7) and (5,-1)


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 (-3,7) and (x%5B2%5D,y%5B2%5D) is the second point (5,-1))


m=%28-1-7%29%2F%285--3%29 Plug in y%5B2%5D=-1,y%5B1%5D=7,x%5B2%5D=5,x%5B1%5D=-3 (these are the coordinates of given points)


m=+-8%2F8 Subtract the terms in the numerator -1-7 to get -8. Subtract the terms in the denominator 5--3 to get 8




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-7=%28-1%29%28x--3%29 Plug in m=-1, x%5B1%5D=-3, and y%5B1%5D=7 (these values are given)



y-7=%28-1%29%28x%2B3%29 Rewrite x--3 as x%2B3



y-7=-x%2B%28-1%29%283%29 Distribute -1


y-7=-x-3 Multiply -1 and 3 to get -3%2F1. Now reduce -3%2F1 to get -3

y=-x-3%2B7 Add 7 to both sides to isolate y


y=-x%2B4 Combine like terms -3 and 7 to get 4

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Answer:



So the equation of the line which goes through the points (-3,7) and (5,-1) is:y=-x%2B4


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=4


Notice if we graph the equation y=-x%2B4 and plot the points (-3,7) and (5,-1), we get this: (note: if you need help with graphing, check out this solver)


Graph of y=-x%2B4 through the points (-3,7) and (5,-1)


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



Answer by chitra(359) About Me  (Show Source):
You can put this solution on YOUR website!
The equation of the line containing the two points is given by:

(x1, y1) and (x2, y2) is given by :

%28y+-+y1%29%2F%28y2+-+y1%29+=++%28x+-+x1%29%2F%28x2+-+x1%29

The given co-ordinates are: (-3, 7) and (5, -1) Substituting for the co-ordiantes for the above formula we get:

%28y+-+7%29%2F%28-1+-+7%29+=++%28x+-+%28-3%29%29%2F%285+-+%28-3%29%29

==> +%28y+-+7%29%2F%28-8%29+=+%28x+%2B+3%29%2F%288%29+

==> %28y+-+7%29+=+-%28x+%2B+3%29

==> y - 7 = - x - 3

==> y - 7 + x + 3 = 0


==> x + y - 4 = 0

is the equation of the straight line

thus, the solution
Regards
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