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Answer:
5x -y = -37
Step-by-step explanation:
One way to find the coefficients A and B is to use the differences of the x- and y-coordinates:
A = Δy = y2 -y1 = 2 -(-3) = 5
B = -Δx = -(x2 -x1) = -(-7 -(-8)) = -1
Then the constant C can be found using either point.
5x -y = 5(-7) -2 = -37
The equation of the line is ...
5x -y = -37
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Additional comment
This approach comes from the fact that the slope of a line is the same everywhere.
[tex]\dfrac{y-y_1}{x-x_1}=\dfrac{y_2-y_1}{x_2-x_1}=\dfrac{\Delta y}{\Delta x}\\\\\Delta x(y-y_1)=\Delta y(x-x_1)\qquad\text{cross multiply}\\\\\Delta y(x-x_1)-\Delta x(y-y_1)=0\qquad\text{subtract y term}\\\\\Delta y(x) -\Delta x(y) = \Delta y(x_1)-\Delta x(y_1)\qquad\text{Ax+By=C form}[/tex]
The "standard form" requires that A be positive, so we chose point 1 and point 2 to make sure that was the case.
