1. 15- Higher-Order Differential Equations -Second-Order Linear Differential Equations with Constant Coefficients and Constant Term -Complex Numbers and Circular Functions -Analysis of the Complex-Root Case -A Market Model with Price Expectations -The Interaction of Inflation and Unemployment -Differential Equations with a Variable Term -Higher-Order Linear Differential Equations

2. 16- Discrete Time: First-order Difference Equation -Discrete Time, Differences, and Difference Equations -Solving a First-Order Difference Equation -The Dynamic Stability of Equilibrium -The Cobweb Model -A Market Model with Inventory -Nonlinear Difference Equation – The Qualitative-Graphic Approach

3. 17- Higher-Order Difference Equations -Second-Order Linear Difference with Constant Coefficients and Constant Term -Samuelson Multiplier-Acceleration Interaction Model -Inflation and Unemployment in Discrete Time -Generalization to Variable-Term and Higher-Order Equations