What is the purpose of the point-slope equation as opposed to the slope-intercept form?

Question

ddcamp · Answer

Sometimes we only know the slope of a line and a point it passes through, but not any of the intercepts.

anonymous · Answer

Could you give an example?

ddcamp · Answer

Say I'm walking on a road that has mile markers every mile. I start somewhere between mile markers, but don't know exactly where. I have a speedometer so I know how fast I'm going, (slope), and a stopwatch. I know that after travelling for 8 minutes (x=8), I pass mile marker 32 (y=32), and I've been walking at a steady rate of .1 miles a minute (m = .1).

Even though I don't know exactly where on the road I started, I can still find a graph that models my walk.