What is the equation of the line that contains the two points (0,-1) and (-1,-3)?
2 answers:
Remark
Right away when the x value of one of the points = 0 then you have the y intercept.
-1 = 0*m + b
b = - 1
So far what you have is y = mx - 1. Now use the two points to get the slope (m)
x1 = 0
x2 = -1
y1 = -1
y2 = - 3
m = (y2 - y1) / (x2 - x1)
m = (-3 - - 1) / (-1 - 0)
m = -2/-1 = 2
The answer to the equation is
y = 2x - 1
Note
The best way to check this is with a graph. The two given points are marked on the graph. The upper one is (0 , -1). The lower one is (-1 , -3). The slope must be correct.
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