Colour by Numbers: Solving Algebraic Equations Without Algebra

A series of Excel models is described. They allow solution of f(x) = 0 by examining change of sign of function values. The function is graphed and change of sign easily detected by a change of colour. Prominent Excel features used are Names, Chart Wizard and Conditional Formatting. Several sample Excel models are available for download, and the paper is intended to be used as a lesson plan for students having some familiarity with derivatives. For comparison and reference purposes, the paper also presents a brief outline of several common equation-solving strategies as an Appendix.