Stage 36 · Limits, Derivatives & Their Applications
36.2.2 The Slope of a Secant Line
36.2 How Fast Things Change: From Average to Instant
Point 2 of 5
36.2.2 The Slope of a Secant Line
Core ideaThe slope of the straight line joining two points on a curve is exactly the average rate of change across that stretch.
Module goal. Use a limit to squeeze "the average pace over a stretch" down into "the pace at this very instant," leading naturally to the heart of the derivative.