Answer:
2
Step-by-step explanation:
You want the slope of a line perpendicular to the line through points (1, 2) and (3, 1).
Slope
You are correct that the slope of the line through the given point is ...
[tex]m=\dfrac{y_2-y_1}{x_2-x_1}=\dfrac{1-2}{3-1}=\dfrac{-1}{2}=-0.5[/tex]
As you say, this is also the slope of a parallel line.
Perpendicular
The slope of a perpendicular line will be the opposite reciprocal of this:
m⊥ = -1/m = -1/(-0.5) = 2
The slope of a perpendicular line is 2.
