Question

The points (1, 6) and (r, -6) lie on a line with slope - 4. Find the missing coordinate r.

Answer 1

49

Explanation:

By the definition of slope, as vertical change over horizontal change, we get

`-4=m = (\Delta y )/(\Delta x) = (r-1)/(-6-6) = -(r-1)/(12)`

By checking the first and the last step of that chain

`-4=-\frac {r-1}{12} \rightarrow r-1=48\rightarrow r= 49`