# Solving Systems of Inequalities

Maximizing profits is a top priority for businesses, and determining the optimal production amount is key. This is often presented as a range of production, where profits are achieved above a certain amount. These ranges are shown using inequalities and are utilized by companies for inventory control, production planning, pricing, and shipping and warehousing management. In this article, we will delve into the topic of systems of inequalities and methods for solving them.What are systems of inequalities?A system of inequalities is a group of inequalities containing one or more variables. These systems are commonly used to find the best solution to a problem.For instance, imagine a bus with a left seat (x) and a right seat (y) that can hold up to 48 people. This can be expressed mathematically as x + y ≤ 48. If we know that the right seat can only accommodate 23 people and the bus is almost full, we can represent this as y < 23. This is a typical system of inequalities problem that can be solved using the methods discussed below.How to solve systems of inequalities?Solving systems of inequalities differs from solving systems of linear equations, as the substitution and elimination methods cannot be used due to the inequality symbols (<, >, ≤, ≥). Instead, these inequalities must be graphed to determine the solutions.In this section, we will learn how to solve systems of inequalities by graphing two or more linear inequalities at the same time. The solution to a system of inequalities is the region where the graphs of all the inequalities intersect. In other words, any pair of coordinates (x, y) within this region will satisfy all of the inequalities. This region is represented by ∩ and shows the intersection of the solution set of each inequality.Steps for solving systems of inequalitiesWhen solving systems of inequalities, follow these steps:1. Isolate y in each inequality.2. Graph the first inequality and determine which side of the coordinate plane should be shaded using the point (0, 0).3. Graph the second inequality and determine which side of the coordinate plane should be shaded using the point (0, 0).4. Shade the region where the two inequalities intersect. If there is no intersection, the system has no solution.Solving systems of inequalities in two variablesTo gain a better understanding of how to solve systems of inequalities, let's examine some examples.Example 1:Solve the following system of inequalities:x + y ≤ 3x ≥ -1Solution:Since y is already isolated in both inequalities, we can immediately graph them. To find the points for our graphs, we will use the intercept method, where when y = 0, x will be the x-intercept and when x = 0, y will be the y-intercept. We can also replace the inequality symbol with an equal sign to make solving for these points easier.For the first inequality, when x = 0, y = 3. When y = 0, x = 3. So, we get y = -x + 3.For the second inequality, when x = -1, y = 0. When y = -1, x = 0. So, we get y = -1.Therefore, the coordinates for the first line are (0, 3) and (3, 0). Because the inequality symbol is ≤, the line will be solid. Using (0, 0) as our test point, we can determine that it falls outside of the shaded region, meaning that we need to shade the opposite side of the line where (0, 0) does not exist.Next, we will graph the second inequality by finding two points using the intercept method. When x = -1, y = 0. When y = -1, x = 0. So, we get y = -x - 1.Therefore, the coordinates for the second line are (-1, 0) and (0, -1). Because the inequality symbol is <, the line will be dotted. Using (0, 0) as our test point, we can determine that it satisfies the inequality. Therefore, we will shade the side of the line where (0, 0) exists.The shaded region where the two lines intersect (the area between the two shaded sides) represents the solution to this system of inequalities.Example 2:Solve the following system of inequalities:x + y ≤ 2x > 1Solution:Using the same method as before, we can find the coordinates for each line:For the first line, when x = 0, y = 2. When y = 0, x = 2. So, we get y = -x + 2.For the second line, when x = 1, y = 0. When y = 0, x = 1. So, we get x = 1.The first line has a solid line because of the ≤ sign, and the second line has a dotted line because of the > sign. Using (0, 0) as our test point, we can determine that it falls outside of the shaded region for the first inequality, so we will shade the opposite side of the line. For the second inequality, (0, 0) does not satisfy it, so we will shade the side where (0, 0) exists. The shaded region where the two lines intersect (the overlap between the two shaded sides) represents the solution to this system of inequalities.

## The Purpose of Solving Systems of Inequalities

Businesses often use systems of inequalities to make important decisions and solve problems. By visually representing these systems on a graph, the intersecting area of the shaded regions illustrates the optimal solution. This approach is a valuable tool for maximizing profits and streamlining operations.

## The Solution of Two Inequalities

The solution of a system of inequalities is found where two shaded regions intersect. Let's work through an example to see this process in action.

## The Process of Solving

To begin, we will graph the first inequality using the intercept method.

When x = 0, y = 4

When y = 0, x = 6

With these points, we can plot the line for the first inequality.

Next, we will graph the second inequality by finding two points using the intercept method.

When x = 0, y = 3

When y = 0, x = 1

Using these points, we can plot the second inequality.

Notice that both lines are parallel, meaning they will never intersect. Such systems have no solutions.

## Solving Systems of Inequalities in One Variable

Systems of inequalities in one variable require finding the range that satisfies the inequality. It is important to keep in mind that systems consist of two separate inequalities that must be solved and then combined for the final solution. Let's explore some examples to better understand this process.

## The Solution Process

We will begin by solving the first inequality separately.

Using algebra, we can isolate the x variable by subtracting 3 from each side of the inequality.

This yields x ≥ 0.

The solution set in interval notation is [0, ∞). Now let's solve the second inequality.

Again, we will isolate the x variable by subtracting 2 from each side of the inequality.

Next, we will multiply both sides by -1, which switches the inequality sign to its opposite.

The solution set in interval notation is (-∞, 4]. The overlapping region of these two sets is the solution, represented by [0, 4].

## The Solution Process

Let's solve the first inequality.

By subtracting 3 from each side, we get y ≥ -3.

The interval notation for this solution set is [-3, ∞). Now, let's solve the second inequality.

Subtracting 6 from each side gives us x ≤ -2.

Multiplying both sides by -1 changes the sign to its opposite, giving us the interval notation of (-∞, 2] for the solution set.

## Understanding Systems of Inequalities - Key Points

• A system of inequalities involves two or more inequalities in one or more variables.
• Systems are used when multiple constraints exist for the solution to a problem.
• The intersection of two inequalities is the solution to the system.
• When the lines of two inequalities are parallel, the system has no solutions.

## How to Solve Systems of Inequalities

If you're wondering how to solve a system of inequalities, follow these steps:

• Solve one inequality for y.
• Graph the line as a solid or dashed line, depending on the inequality symbol.
• Shade the region that satisfies the inequality.
• Repeat for each inequality.
• The solution set is the overlapping area of all inequalities.

If graphing isn't your preferred method, you can express the solution set in set-builder notation.

Algebraically, you can solve a system of inequalities by eliminating fractions, simplifying, and isolating the unknown variable.

Now that you grasp the fundamentals of solving systems of inequalities, try some practice problems to enhance your skills. With practice, you'll become a master in no time!

## A Step-by-Step Guide to Solving Systems of Linear Inequalities with Graphing

Solving a system of linear inequalities may seem daunting, but by following these standard steps, you can easily find a solution. This article will discuss how to solve a system of linear inequalities using graphing.

First, let's clarify what a system of linear inequalities is.

## A Guide to Solving Systems of Linear Inequalities through Graphing

Solving a system of linear inequalities, composed of two or more linear inequalities with two or more variables, can seem intimidating. However, with the use of graphing, it becomes a simple and efficient process. In this article, we will walk you through the steps for solving a system of linear inequalities using graphing.

Step 1: Graph each inequality individually

To begin, graph each inequality in the same coordinate plane separately. This means rewriting the inequality in slope-intercept form: y = mx + b. Plot the y-intercept (b) on the y-axis and use the slope (m) to find at least one more point on the line. Then, draw a dashed line if the inequality includes "<" or ">", or a solid line if it includes "<=" or ">=".

Step 2: Identify the overlapping region

Next, take a look at the overlapping region between the lines. This area represents the points that satisfy all of the provided inequalities, making it the possible solution to the system of linear inequalities.

Now, it is important to determine whether the solution lies in the shaded or unshaded region. To do so, pick a point within the overlapping region and substitute its coordinates into each inequality. If the point satisfies all of the inequalities, it belongs to the shaded region. Conversely, it belongs to the unshaded region if it does not satisfy the inequalities.

Step 4: Represent the solution graphically

The final step is to visually represent the solution. If the solution is in the shaded region, draw a shaded area on the graph. If it is in the unshaded region, use a dotted line to represent it. And if there is no solution, mark an X through the graph.

And that's all there is to it! You have now successfully solved a system of linear inequalities using graphing. Remember to always check your solution for accuracy and ensure it satisfies all of the given inequalities.

By following these four simple steps - graphing each inequality, identifying the overlapping region, checking for shaded or unshaded regions, and representing the solution graphically - you can easily solve any system of linear inequalities. With practice, solving such systems will become second nature to you. Happy graphing!