**Chapter 2Graphs of Linear Equations and Inequalities**

2.1 Graphing Equations

2.2 Writing Linear Equations

2.3 Direct Variation

2.4 Scatter Plots and Lines of Regression

2.5 Graphing Linear Inequalities

**2.1 Graphing Equations**

In Chapter 1, you solved equations and inequalities in one variable and illustrated the solutions on a number line. An equation or inequality in two variables often uses the variables *x* and *y*, and the solutions are the ordered pairs (*x, y*) that make the equation or inequality true. The ordered-pair solutions can be graphed on a coordinate plane.

**Linear vs. Nonlinear**

A *linear equation* is an equation whose solutions form a straight line on a graph. An equation that produces a graph that is not a straight line is *nonlinear*.