21.7.6 Looking Back at the Line, Ahead to the Curve
Core ideaA linear function changes at a steady pace, so it's a straight line; but if each step's increase itself keeps changing, the graph bends — and that opens the door to inverse proportion.
Module goal. Pull together modeling, recovering formulas, reading graphs, and equations and inequalities to solve real situations — and plant a contrast that sets up the nonlinear change of the next stage.