21.5 Linear Functions Tie Together Equations and Inequalities
Point 4 of 5
21.5.4 Comparing Heights to Solve k1x+b1 > k2x+b2
Core idea
Use the crossing point as the boundary and see which line is higher — that tells you which stretch of x makes one expression bigger than the other.
Module goal. Use the lens of the straight line to unify linear equations and inequalities, turning algebraic solving into "reading heights off the graph."
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