21.3.2 The Signs of k and b Decide Which Quadrants It Passes
Core ideaNotice which way the line climbs and which side of the y-axis it crosses, and you can count off the quadrants it travels through.
Module goal. Systematically describe how the signs of k and b decide a line's direction, whether it rises or falls, and which quadrants it visits — upgrading you from "able to draw" to "able to read."