Answer
The points indeed lie on the same line.
Work Step by Step
To find the slope, we use the formula:
$m=\dfrac{y_2-y_1}{x_2-x_1}$
So, let's first find the slope between A and B:
$m=\dfrac{1-5}{6-2}=\dfrac{-4}{4}=-1$
Now, let's find the slope between B and C:
$m=\dfrac{-1-1}{8-6}=\dfrac{-2}{2}=-1$
Finally, let's find the slope between A and C:
$m=\dfrac{-1-5}{8-2}=\dfrac{-6}{6}=-1$
They all have a slope of -1; therefore, they all lie on the same line.
