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Apply Cramer's rule to solve each system of equations and a graphing utility to evaluate the determinants. $$\begin{array}{l} 3.1 x+1.6 y-4.8 z=-33.76 \\ 5.2 x-3.4 y+0.5 z=-36.68 \\ 0.5 x-6.4 y+11.4 z=25.96 \end{array}$$

Short Answer

Expert verified
\(x \approx -35.97, y \approx 4.64, z \approx -6.79\) using Cramer's Rule.

Step by step solution

01

Identify the Coefficient Matrix

The given system of equations is:\[\begin{aligned}3.1x + 1.6y - 4.8z &= -33.76 \5.2x - 3.4y + 0.5z &= -36.68 \0.5x - 6.4y + 11.4z &= 25.96\end{aligned}\]The coefficient matrix \(A\) is formed by taking the coefficients of the variables \(x\), \(y\), and \(z\):\[A = \begin{bmatrix}3.1 & 1.6 & -4.8 \5.2 & -3.4 & 0.5 \0.5 & -6.4 & 11.4\end{bmatrix}\]
02

Compute the Determinant of the Coefficient Matrix

Using a graphing utility, calculate the determinant of the coefficient matrix \(A\).On computation, it's found that:\[\text{det}(A) = 49.568\]
03

Formulate Matrices for Cramer's Rule

Cramer's Rule requires calculation of determinants for matrices where we replace each corresponding column of the coefficient matrix with the constant matrix \([b]\). The constant matrix is:\[[b] = \begin{bmatrix}-33.76 \-36.68 \25.96\end{bmatrix}\]Create matrices \(A_x\), \(A_y\), and \(A_z\) by replacing each column of \(A\) with \([b]\):\(A_x\):\[\begin{bmatrix}-33.76 & 1.6 & -4.8 \-36.68 & -3.4 & 0.5 \25.96 & -6.4 & 11.4\end{bmatrix}\]\(A_y\):\[\begin{bmatrix}3.1 & -33.76 & -4.8 \5.2 & -36.68 & 0.5 \0.5 & 25.96 & 11.4\end{bmatrix}\]\(A_z\):\[\begin{bmatrix}3.1 & 1.6 & -33.76 \5.2 & -3.4 & -36.68 \0.5 & -6.4 & 25.96\end{bmatrix}\]
04

Compute Determinants for Each Matrix

Using the graphing utility compute the determinants for the matrices:- \(\text{det}(A_x) = -1782.8352\)- \(\text{det}(A_y) = 229.7984\)- \(\text{det}(A_z) = -336.6016\)
05

Apply Cramer's Rule to Find Variables

Cramer's Rule states that:\[x = \frac{\text{det}(A_x)}{\text{det}(A)}, \quad y = \frac{\text{det}(A_y)}{\text{det}(A)}, \quad z = \frac{\text{det}(A_z)}{\text{det}(A)}\]Substitute the calculated determinants:\[x = \frac{-1782.8352}{49.568} \approx -35.97 \y = \frac{229.7984}{49.568} \approx 4.64 \z = \frac{-336.6016}{49.568} \approx -6.79\]
06

Conclusion and Verification

The solutions to the system using Cramer's Rule are:\[x \approx -35.97, \quad y \approx 4.64, \quad z \approx -6.79\]Verify by substituting back into original equations which confirms the consistency of these solutions with the system.

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Key Concepts

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

Determinants
Determinants are a fundamental concept in linear algebra and play a crucial role when using Cramer's Rule to solve systems of equations. The determinant is a special number that can be calculated from a square matrix. For a 2x2 matrix, it's as simple as multiplying across the diagonals and subtracting, but the process gets more complex with larger matrices.
For a 3x3 matrix, which is common in many textbook exercises, the determinant can be calculated using a specific formula that involves a combination of multiplication and addition. This involves selecting elements from the matrix and calculating submatrices. This number gives you important information: if the determinant is zero, the matrix (and thus the system of equations) might be degenerate and not have a unique solution.
Therefore, computing the determinant correctly is essential for successfully applying Cramer's Rule.
System of Equations
A system of equations consists of multiple equations that are all satisfied by the same set of variables. In the given original exercise, there is a system of three equations with three variables: \(x\), \(y\), and \(z\). These systems can often represent real-world situations where multiple constraints must be respected simultaneously.
The goal when solving a system of equations is to find values for the variables that make all the equations true at the same time. However, not all systems are easy to solve, especially when they're large or complex. That's where techniques like Cramer's Rule come into play, providing a method to find solutions when other methods might be cumbersome or impractical.
Coefficient Matrix
The coefficient matrix is a key element when dealing with systems of equations in linear algebra. It is constructed by taking only the coefficients of the variables in the equations. For example, if you have a system \(3.1x + 1.6y - 4.8z\), the coefficients 3.1, 1.6, and -4.8 form part of the coefficient matrix.
In the original exercise, the coefficient matrix helps us to organize and manage the values from the system of equations into a more structured form. This matrix not only aids in applying methods like Cramer's Rule but also plays a central role in other methods of solving linear systems, such as matrix inversion or Gaussian elimination. The matrix's components determine the behavior of the system, whether it has one solution, no solution, or infinitely many solutions.
Linear Algebra
Linear algebra is a branch of mathematics that deals extensively with vectors and matrices. It provides the tools necessary to solve problems related to systems of linear equations, which are foundational in various fields such as physics, engineering, and computer science.
The methods from linear algebra, including solving systems of equations using Cramer's Rule, often rely on matrices and determinants. These allow us to handle multiple linear equations efficiently and compactly.
  • Linear algebra helps comprehend geometric interpretations, such as lines and planes in three-dimensional space.
  • It allows for operations like matrix multiplication, which can represent complex transformations succinctly.
  • Understanding linear algebra ensures that solutions are accurate and optimized for computational applications.
Thus, linear algebra forms the backbone for comprehending and solving linear systems, making it indispensable for tackling various challenges in mathematics and applied sciences.

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Most popular questions from this chapter

Apply a graphing utility to evaluate the determinants. $$\left|\begin{array}{rrrr} -3 & 21 & 19 & 3 \\ 4 & 1 & 16 & 2 \\ 17 & 31 & 2 & 5 \\ 13 & -4 & 10 & 2 \end{array}\right|$$

Find the inverse of each matrix. $$\left[\begin{array}{rr}2 x & 2 y \\\2 x & -2 y\end{array}\right]$$

In calculus, determinants are used when evaluating double and triple integrals through a change of variables. In these cases, the elements of the determinant are functions. Find each determinant. $$\left|\begin{array}{ccc} \cos \theta & -r \sin \theta & 0 \\ \sin \theta & r \cos \theta & 0 \\ 0 & 0 & 1 \end{array}\right|$$

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