Skip to main content
Ch. 5 - Systems of Equations and Inequalities
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
All textbooksBlitzer 8th EditionCh. 5 - Systems of Equations and InequalitiesProblem 5
Chapter 6, Problem 5

An objective function and a system of linear inequalities representing constraints are given. a. Graph the system of inequalities representing the constraints. b. Find the value of the objective function at each corner of the graphed region. c. Use the values in part (b) to determine the maximum value of the objective function and the values of x and y for which the maximum occurs.
Objective function z = 3x + 2y with constraints x, y ≥ 0; 2x + y ≤ 8; x + y ≥ 4 shown.

Verified step by step guidance
1
Step 1: Identify the constraints and the objective function. The objective function is given by \(z = 4x + 6y\). The constraints are the inequalities: \(x \geq 0\), \(y \geq 0\), \(3x + 7y \geq 21\), and \(10x + 7y \leq 70\).
Step 2: Graph the system of inequalities. Start by graphing the boundary lines for each inequality: \(x = 0\), \(y = 0\), \(3x + 7y = 21\), and \(10x + 7y = 70\). Use these lines to determine the feasible region that satisfies all inequalities simultaneously.
Step 3: Find the corner points (vertices) of the feasible region by solving the systems of equations formed by the intersection of the boundary lines. For example, find the intersection of \(3x + 7y = 21\) and \(10x + 7y = 70\), and also check intersections with the axes where \(x=0\) or \(y=0\).
Step 4: Evaluate the objective function \(z = 4x + 6y\) at each corner point found in Step 3. Substitute the \(x\) and \(y\) values of each vertex into the objective function to find the corresponding \(z\) values.
Step 5: Compare the values of \(z\) obtained at each corner point to determine the maximum value. Identify the \(x\) and \(y\) coordinates where this maximum occurs, which will be the solution to the optimization problem.

Verified video answer for a similar problem:

This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
10m
Was this helpful?

Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Graphing Systems of Linear Inequalities

Graphing systems of linear inequalities involves plotting each inequality on the coordinate plane and identifying the region that satisfies all constraints simultaneously. This region, called the feasible region, is typically a polygon bounded by the lines representing the inequalities. Understanding how to shade and interpret these regions is essential for solving optimization problems.
Recommended video:
Guided course
6:19
Systems of Inequalities

Corner Points (Vertices) of the Feasible Region

The feasible region formed by the system of inequalities is a convex polygon, and its corner points (vertices) are where the boundary lines intersect. These points are critical because, according to the Linear Programming Fundamental Theorem, the maximum or minimum value of a linear objective function occurs at one of these vertices.
Recommended video:
Guided course
05:10
Graphs & the Rectangular Coordinate System

Evaluating the Objective Function at Corner Points

The objective function, such as z = 4x + 6y, is evaluated at each vertex of the feasible region to determine which point yields the maximum or minimum value. By substituting the coordinates of each corner point into the objective function, one can identify the optimal solution and the corresponding values of x and y.
Recommended video:
4:26
Evaluating Composed Functions
Related Practice
Textbook Question

In Exercises 1–4, determine whether the given ordered pair is a solution of the system. (2, 5) 2x + 3y = 17 x + 4y = 16

11
views
Textbook Question

Find the value of the objective function at each corner of the graphed region. What is the maximum value of the objective function? What is the minimum value of the objective function? 1. Objective Function z=40x+50y

1
views
Textbook Question

In Exercises 5–18, solve each system by the substitution method. x + y = 4 y = 3x

1
views
Textbook Question

Write the form of the partial fraction decomposition of the rational expression. It is not necessary to solve for the constants. 5x2−6x+7(x−1)(x2+1)\(\frac{5x^2 - 6x + 7}{(x - 1)(x^2 + 1)}\)

Textbook Question

In Exercises 1–8, write the form of the partial fraction decomposition of the rational expression. It is not necessary to solve for the constants. (3x+16)/(x + 1) (x − 2)²

7
views
Textbook Question

In Exercises 1–18, solve each system by the substitution method. {y=x2−4x−10y=−x2−2x+14\(\begin{cases}\)y = x^2 - 4x - 10 \(\y\) = -x^2 - 2x + 14\(\end{cases}\)