SOLUTION: Find the slope of the line containing the given pair of points. If the slope is undefined, state so. (1, 2) and (9, 12) please help

Question 294130: Find the slope of the line containing the given pair of points. If the slope is undefined, state so.
(1, 2) and (9, 12) please help
Answer by Alan3354(69443) (Show Source): You can put this solution on YOUR website!
Given 2 points example.
Find the equation of the line thru the points (2,1) and (3,5)
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This is a 2 step process. First find the slope of the line thru the points.
slope, m = diffy/diffx
m = (5-1)/(3-2)
m = 4
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Now use y = mx + b with either point to find b, the y-intercept.
y = mx + b
5 = 4*3 + b
b = -7
-------
y = mx + b
y = 4x - 7 is the answer.
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Another approach using determinants:
|x y 1|
|2 1 1| = 0
|3 5 1|
--------
x(1-5) - y(2-3) + 1(10-3) = 0
-4x + y + 7 = 0
y = 4x - 7
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For further assistance, or to check your work, email me via the thank you note
or at MoralLoophole@aol.com

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