## Intermediate Algebra (12th Edition)

Slope is defined as: $\displaystyle slope=\frac{rise}{run}$ To find the slope of $CD$, we need to find the rise and run from $C$ to $D$. From the graph, we see that: $rise=-7$ units $run=0$ units (since the line is vertical) Thus: $slope=\frac{-7}{0}=undefined$ (vertical "infinite" slope)