21.1 From Coordinates to Direct Proportion: The Plainest Kind of Change
Point 5 of 5
21.1.5 k Sets the Line's Direction and Steepness
Core idea
When k>0 the line climbs to the upper right and when k<0 it slides to the lower right; the bigger |k| is the steeper it gets, and k is the slope.
Module goal. Building on the coordinate plane and the idea of a function, meet the simplest family of functions — direct-proportion functions — and lock in the core picture: a graph that's a straight line through the origin.
eastmath.com · 21.1 From Coordinates to Direct Proportion: The Plainest Kind of Change · 21.1.5 k Sets the Line's Direction and Steepness