Question

Graph the inequality: \(\mathrm{y} \geq \mathrm{x}-1\).

Short answer

The short answer to graph the inequality \(y \geq x - 1\) is as follows: 1. Draw the line \(y = x - 1\) on the graph using points such as (-1, -2), (0, -1), and (1, 0). Make this line solid since it's a "greater than or equal to" inequality. 2. Choose a test point, like the origin (0, 0), and check if it satisfies the inequality. Since 0 ≥ -1, shade the region containing the test point, which represents the solution \(y \geq x - 1\).

Step-by-step solution

Graph the line y = x - 1

First, draw the line y = x - 1 on the graph. This is the boundary between the two regions defined by the inequality y ≥ x - 1. We need to graph this line using some points, such as (-1, -2), (0, -1), and (1, 0).

Shade the region representing y ≥ x - 1

The inequality is y ≥ x - 1, which means that the values of y must be greater than or equal to the values of x - 1. Choose a test point (for example, the origin (0,0)) and check if it satisfies the inequality: 0 ≥ 0 - 1 → 0 ≥ -1 The test point (0,0) satisfies the inequality, so the region containing the point (0,0) must be shaded to represent the solution y ≥ x - 1. If the test point didn't satisfy the inequality, we would shade the opposite region. Also, as it is a "greater than or equal to" inequality, the line y = x - 1 must be a solid line to indicate that points on the line are also part of the solution.

Key concepts

Linear Inequalities

Understanding linear inequalities is crucial for students entering the world of algebra. These are similar to linear equations but use inequality symbols such as '\textgreater', '\textless', '\textgreater=', and '\textless=' instead of an equals sign. For example, the inequality \(y \textgreater= x - 1\) indicates a relationship where \(y\) is greater than or equal to \(x\) minus 1. When graphing a linear inequality, you will first draw the boundary line, which is the related linear equation (when the inequality symbol is replaced with an equals sign), and this line will either be solid if the inequality includes 'equal to' (\textgreater= or \textless=) or dashed if it does not (\textgreater or \textless). Then the area of the graph that satisfies the inequality is shaded, representing all the possible solutions.

To give students a better understanding, a simple trick is using two points to draw the boundary line. The more points you use, the more accurate the graph, but two points are often sufficient to determine a straight line. This basic foundation sets the stage for accurately graphing and solving inequalities.

Shading Regions

When dealing with shading regions on a graph, we identify the area where all the solutions of an inequality lie. After drawing the boundary line of an inequality, we choose one of the two halves of the graph. The correct half is determined by the inequality symbol. For instance, with the inequality \(y \textgreater= x - 1\), the region above the line includes all the points where the \(y\)-values are greater than the corresponding \(x\)-values minus 1, thus satisfying the inequality. To explain this in the simplest way possible: If the inequality symbol points upwards (\(\textgreater\) or \(\textgreater=\)), shade above the line; if it points downwards (\(\textless\) or \(\textless=\)), shade below the line. This visual demonstration aids students in seeing the continuum of answers that fulfill the inequality, reinforcing their comprehension of linear inequalities.

Inequality Solutions

The inequality solutions for a graphed linear inequality consist of a range of values, forming a region on the graph. This area includes all the ordered pairs (\(x, y\)) that satisfy the inequality. It is vital to note that an inequality does not have just a single solution but many. For example, in the inequality \(y \textgreater= x - 1\), every point in the shaded area is a solution to the inequality. This can be especially tricky for students who are accustomed to finding one solution for an equation. A good way to make this clear is to pick multiple points from the shaded region and demonstrate that they all satisfy the inequality. Equally important is to emphasize that all points on the boundary line are part of the solution set if the inequality includes 'equal to' (indicated by the solid line) and excluded if it does not (indicated by a dashed line).

Test Point Method

The test point method is a foolproof technique for determining which side of the boundary line to shade for a linear inequality. Select a point that's not on the line (the origin (0,0) is often a convenient choice) and substitute its coordinates into the inequality. If the inequality holds true, then the region containing the test point is shaded. If the inequality does not hold, the opposite region is shaded. For example, when graphing \(y \textgreater= x - 1\), we chose the origin (0,0) as a test point. Substituting into the inequality gives us \(0 \textgreater= 0 - 1\), which simplifies to \(0 \textgreater= -1\). Since this is true, the region that includes (0,0) is shaded. This test point method can be particularly effective in dispelling confusion about which side of the line represents the solution set and should be coupled with the initial graphing steps for clear and comprehensive learning.