Sign of a Product of Two Numbers

This example demonstrates the sign change规律 of the product of two numbers through dynamic graphics, visually showing the relationship between signs and factors. Core math concepts include sign rules for numbers, multiplication properties, and function graph characteristics. GeoGebra commands like Point, Line, Intersect are used to create points, lines, and intersections, with objects f, g representing functions, and text objects for annotations. Suitable for middle school and above mathematics education, helping students understand product sign determination and function graph analysis.