## Calculus (3rd Edition)

The slope of the line passing through $(2,2), (0.5,1)$ is: $slope=\dfrac{y_1-y_2}{x_1-x_2}=\frac{2-1}{2-0.5}= \frac{1}{1.5}= \frac{2}{3}$. The slope of the line passing through $(2,2), (1,1.2)$ is: $slope=\dfrac{y_1-y_3}{x_1-x_3}=\frac{2-1.2}{2-1}= 0.8= \frac{4}{5} \neq \frac{2}{3}$. Since the slopes are not equal, these three points do not line on the same line.