What is the slope of the line that passes through the points (2, -1) and (2,0)?
(2,-1),(2,0)
y2 - y1
-------- = slope
x2 - x1
0 - (-1)
--------- {substituted into slope formula}
2 - 2
1
--- {subtracted}
0
= undefined {it is impossible to divide a number by 0}
The slope is "undefined". Also, this would be a vertical line.
Horizontal lines have slopes of 0, such as 0/3.
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