SOLUTION: Determine if the points (1,5),(2,3) and (-2,-11) are collinear.

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Question 1063614: Determine if the points (1,5),(2,3) and (-2,-11) are collinear.
Answer by reviewermath(1029) About Me  (Show Source):
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Q:
Determine if the points (1,5),(2,3) and (-2,-11) are collinear.
Tutorial:
The 3 points are collinear if they lie on the same line.
First, we get get the equation of the line containing the first 2 points.
We compute the slope of the points (1,5) and (2,3).
The slope is equal to "change in y" divided by "change in x"
slope, m = %283+-+5%29%2F%282+-+1%29+=+-2
Next, we use the point-slope form y+-+y%5B1%5D+=+m%28x+-+x%5B1%5D%29
We choose (x%5B1%5D, y%5B1%5D) = (1, 5)
y - 5 = -2(x - 1)
y - 5 = -2x + 2
y = -2x + 7 is the equation of the line containing (1, 5) and (2, 3).
Next, we check if the 3rd point (-2, -11) satisfies the equation y = -2x+7.
If x = -2, then y = -2(-2)+7 = 11 (NOT equal to -11)
Therefore, the 3 given points are NOT collinear