Lesson 21
From One to TwoVariable Inequalities
 Let’s look at inequalities in two dimensions.
21.1: Describing Regions of the Plane
For each graph, what do all the ordered pairs in the shaded region have in common?
21.2: More or Less
 Write at least 3 values for \(x\) that make the inequality true.
 \(x < \text{}2\)
 \(x+2 > 4\)
 \(2x1 \leq 7\)

Graph the solution to each inequality on a number line.

Using the inequality \(x < \text{}2\), write 3 coordinate pairs for which the \(x\)coordinate makes the inequality true. Use the coordinate plane to plot your 3 points.
21.3: Above or Below the Line

Graph the line that represents the equation \(y = 3x4\)
 Is the point \((4,8)\) on the line?
 Explain how you know using the graph.
 Explain how you know using the equation.
 Use the 3 points \((5, a), (\text7,b) \) and \((c,20)\)
 Write values for \(a, b,\) and \(c\) so that the points are on the line.
 Write values for \(a, b,\) and \(c\) so that the points are above the line.
 Write values for \(a, b,\) and \(c\) so that the points are below the line.