SOLUTION: Need to solve this by hand. Please help, thanks! How do I find the equation of the line passing through points (1,19) and (-1,-3)

Algebra ->  Linear-equations -> SOLUTION: Need to solve this by hand. Please help, thanks! How do I find the equation of the line passing through points (1,19) and (-1,-3)      Log On


   



Question 1021649: Need to solve this by hand. Please help, thanks!
How do I find the equation of the line passing through points (1,19) and (-1,-3)

Found 3 solutions by macston, FrankM, ewatrrr:
Answer by macston(5194) About Me  (Show Source):
You can put this solution on YOUR website!
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P%5B1%5D=(x%5B1%5D,y%5B1%5D)=(1,19)
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P%5B2%5D=(x%5B2%5D,y%5B2%5D)=(-1,-3)
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Find the slope (m):
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m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29
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m=%28-3-19%29%2F%28-1-1%29=-22%2F-2=11
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For the equation, use slope-intercept form (y=mx+b):
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m=11
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y=11x+b
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Use either of the points P%5B1%5D or P%5B2%5D to find b:
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Using P%5B1%5D, x=1 and y=19:
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y=11x+b
19=11(1)+b
19=11+b
8=b
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Using m=11 and b=8:
y=mx+b
y=11x+8
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ANSWER: The equation is: y=11x+8
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CHECK: (Using P%5B2%5D)
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x=-1 and y=-3
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y=11x+8
-3=11(-1)+8
-3=-11+8
-3=-3
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Answer by FrankM(1040) About Me  (Show Source):
You can put this solution on YOUR website!
The equation for slope, given 2 points:
m=%28y%5B2%5D-y%5B1%5D%29%2F%28x%5B2%5D-x%5B1%5D%29

(1,19) and (-1,-3)

m=%28-3-19%29%2F%28-1-1%29

m=%28-22%29%2F%28-2%29=11

Now the Point-Slope Equation, when you have a slope and a point.

%28y-y%5B1%5D%29=m%28x-x%5B1%5D%29

m=11 (1,19)

%28y-19%29=11%28x-1%29

y-19=11x-11

y=11x%2B8

Plug in both points and see that they fit the equation.





Answer by ewatrrr(24785) About Me  (Show Source):
You can put this solution on YOUR website!

Hi
How do I find the equation of the line passing through points (1,19) and (-1,-3)
Takes two steps:
I. find slope m =%28y%5B1%5D+-+y%5B2%5D%29%2F%28x%5B1%5D+-+x%5B2%5D+%29
(1,19) and
(-1,-3 m = 22/2 = 11
II. Use y = mx + b and P(1,19)
y = 11x + b
19 = (11)(1) + b Substitute x and y values from P(1,19)
19-11 = b
8 = b
Then
y = 11x + 8 0r Standard form: 11x-y = -8