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Use Gauss-Jordan row reduction to solve the given systems of equation. We suggest doing some by hand, and others using technology. HINT [See Examples 1-6.] $$ \begin{aligned} &2 x+3 y=2 \\ &-x-\frac{3 y}{2}=-\frac{1}{2} \end{aligned} $$

Short Answer

Expert verified
The given system of equations is inconsistent, meaning it has no solution. This was determined by performing Gauss-Jordan row reduction and obtaining an invalid equation in the process. The final augmented matrix was: $$ \left[\begin{array}{cc|c} 1 & \frac{3}{2} & 1 \\ 0 & 0 & \frac{1}{2} \end{array}\right] $$

Step by step solution

01

Write the system as an augmented matrix

First, let's represent the given system of equations in the form of an augmented matrix: $$ \left[\begin{array}{cc|c} 2 & 3 & 2 \\ -1 & -\frac{3}{2} & -\frac{1}{2} \end{array}\right] $$
02

Gauss-Jordan row reduction

Now, we will perform row reductions by following these steps: 1. Make the element (1,1) equal to 1 (pivot). 2. Make the elements below the pivot equal to 0. 3. Move to the next diagonal element (2,2) and make it equal to 1 (pivot). 4. Make the elements above the pivot equal to 0. First, we'll make element (1,1) equal to 1 by dividing the first row by 2: $$ \left[\begin{array}{cc|c} 1 & \frac{3}{2} & 1 \\ -1 & -\frac{3}{2} & -\frac{1}{2} \end{array}\right] $$ Next, we'll make the element (2,1) equal to 0 by adding the first row to the second row: $$ \left[\begin{array}{cc|c} 1 & \frac{3}{2} & 1 \\ 0 & 0 & \frac{1}{2} \end{array}\right] $$ At this point, the row reduction procedure reveals that the second equation is invalid \(0 \neq \frac{1}{2}\), therefore the system of equations has no solution. The result is an inconsistent system.

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Key Concepts

These are the key concepts you need to understand to accurately answer the question.

System of Linear Equations
A system of linear equations is a collection of one or more equations involving the same variables. Usually, the goal is to find the values for each variable that will make all of the equations true simultaneously. For example, the system given in the exercise involves two equations with two variables, x and y.

When dealing with systems, there are three possible types of solutions: a unique solution where there's exactly one set of values for the variables that solves all the equations; infinitely many solutions where there are endless combinations of values that work; and no solution, where no set of values will satisfy all of the equations at once, which is also referred to as an inconsistent system.
Augmented Matrix
An augmented matrix is a compact way to represent a system of linear equations. It includes all the coefficients of the variables on the left side and the constants from the right side of the equations, all in one matrix. This layout makes it easier to manipulate the system using matrix operations. In the exercise, the system is transformed into an augmented matrix with two rows, each representing an equation, and three columns — two for the coefficients of x and y, and one for the constant terms.

The augmented matrix is a useful tool in performing Gaussian elimination or Gauss-Jordan row reduction, as it simplifies the visualization and execution of operations needed to solve the linear system.
Inconsistent System
An inconsistent system of equations is one in which no solution exists. This happens when the equations contradict each other, meaning they do not intersect at any point if plotted graphically. In terms of matrices, an inconsistency becomes apparent during row reduction when you obtain a row with all zeros in the coefficients but a non-zero constant in the augmented part. For instance, the second row in the final matrix of the exercise results in an equation of the form 0x + 0y = 1/2, which is impossible, indicating the system is inconsistent.
Row Reduction Steps
Row reduction is a systematic process used to solve systems of linear equations. Here are the basic steps:
  • Making a Pivot: Select a diagonal element and turn it into 1 (if it's not already). This element is known as a 'pivot.'
  • Zero Below Pivot: Eliminate all elements below the pivot by making them 0, typically through row addition or subtraction.
  • Move to Next Pivot: Proceed to the next diagonal element, turning it into another pivot, and repeat the process of creating zeroes below it.
  • Zero Above Pivot: Once you have 1s down the diagonal, eliminate the numbers above each pivot.
The exercise provided walks through these steps, but it stops once an inconsistency is found. This step-by-step approach, while systematic, still requires careful attention to notice when an equation has no solution, which is as important as solving for the variables when they do exist.

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Most popular questions from this chapter

Use Gauss-Jordan row reduction to solve the given systems of equation. We suggest doing some by hand, and others using technology. HINT [See Examples 1-6.] $$ \begin{aligned} x+y+5 z &=1 \\ y+2 z+w &=1 \\ x+y+5 z+w &=1 \\ x+2 y+7 z+2 w &=2 \end{aligned} $$

Pollution Joe Slo, a college sophomore, neglected to wash his dirty laundry for 6 weeks. By the end of that time, his roommate had had enough and tossed Joe's dirty socks and T-shirts into the trash, counting a total of 44 items. (A pair of dirty socks counts as one item.) The roommate noticed that there were three times as many pairs of dirty socks as T-shirts. How many of each item did he throw out?

Urban Community College is planning to offer courses in Finite Math, Applied Calculus, and Computer Methods. Each section of Finite Math has 40 students and earns the college \(\$ 40,000\) in revenue. Each section of Applied Calculus has 40 students and earns the college \(\$ 60,000\), while each section of Computer Methods has 10 students and earns the college \(\$ 20,000\). Assuming the college wishes to offer a total of six sections, to accommodate 210 students, and to bring in \(\$ 260,000\) in revenues, how many sections of each course should it offer? HINT [See Example 2]

The Enormous State University Good Works Society recently raised funds for three worthwhile causes: the Math Professors' Benevolent Fund (MPBF), the Society of Computer Nerds (SCN), and the NY Jets. Because the society's members are closet jocks, the society donated twice as much to the NY Jets as to the MPBF, and equal amounts to the first two funds (it is unable to distinguish between mathematicians and nerds). Further, for every \(\$ 1\) it gave to the MPBF, it decided to keep \(\$ 1\) for itself; for every \(\$ 1\) it gave to the SCN, it kept \(\$ 2\), and for every \(\$ 1\) to the Jets, it also kept \(\$ 2\). The treasurer of the Society, Johnny Treasure, was required to itemize all donations for the Dean of Students, but discovered to his consternation that he had lost the receipts! The only information available to him was that the society's bank account had swelled by \(\$ 4,200\). How much did the society donate to each cause?

Equilibrium Price At the start of December 2001 , the retail price of a \(25 \mathrm{~kg}\) bag of cornmeal was \(\$ 10\) in Zambia, while by the end of the month, the price had fallen to \(\$ 6 .{ }^{11}\) The result was that one retailer reported an increase in sales from 3 bags/ day to 5 bags/day. Assume that the retailer is prepared to sell 18 bags/day at \(\$ 8\) and 12 bags/day at \(\$ 6\). Obtain linear demand and supply equations, and hence compute the retailer's equilibrium price.

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