## 9 Systems of Equations and Inequalities

**Chapter Outline**

**9.1** Systems of Linear Equations

**9.2** Determinants and Cramer’s Rule

**9.3** Systems of Nonlinear Equations

**9.4** Systems of Inequalities

**9.5** Partial Fractions

Chapter 9 Review Exercises

**9.1 Systems of Linear Equations**

**Introduction** Recall from Section 2.3 that a **linear equation in two variables** *x* and *y* is any equation that can be put in the form *ax* + *by* = *c*, where *a* and *b* are real numbers and not both zero. In general, a **linear equation in ***n* variables *x*_{1}, *x*_{2}, …., *x*_{n} is an equation of the form ...