Graphing Linear Inequalities
Students learn to graph inequalities in two variables. For example, to graph y < x + 2, the first step is to graph the boundary line y = x + 2, using the chart method from lesson 4B. Note that greater than or less than means that the boundary line will be dotted, and greater than or equal to or less than or equal to means that the boundary line will be solid. To determine which side of the boundary line to shade, substitute a test point, such as (0, 0), into the original inequality, y < x + 2. Since (0) < (0) + 2, or 0 < 2, is a true statement, the side of the line that contains the point (0, 0) is shaded.