Chapter 16: Problem 27
Determine by matrix multiplication whether or not \(A\) is the proper matrix of solution values. $$\begin{array}{ll}3 x-2 y=-1 & A=\left[\begin{array}{l}1 \\\2\end{array}\right] \\ 4 x+y=6\end{array}$$
Short Answer
Expert verified
Yes, matrix \( A \) provides the correct solution for the system of equations.
Step by step solution
01
Understand the Problem
We need to verify if the matrix \( A = \begin{bmatrix} 1 \ 2 \end{bmatrix} \) is a solution for the system of equations. This involves computing the product of the coefficient matrix and matrix \( A \), and checking if it equals the result matrix for the system.
02
Define the Coefficient Matrix and Vector
The coefficient matrix from the system of equations is \( C = \begin{bmatrix} 3 & -2 \ 4 & 1 \end{bmatrix} \). The matrix \( A = \begin{bmatrix} 1 \ 2 \end{bmatrix} \) is the one we are testing as a possible solution vector.
03
Perform Matrix Multiplication
Multiply the coefficient matrix \( C \) by matrix \( A \):\[ \begin{bmatrix} 3 & -2 \ 4 & 1 \end{bmatrix} \begin{bmatrix} 1 \ 2 \end{bmatrix} = \begin{bmatrix} 3(1) + (-2)(2) \ 4(1) + 1(2) \end{bmatrix} = \begin{bmatrix} 3 - 4 \ 4 + 2 \end{bmatrix} = \begin{bmatrix} -1 \ 6 \end{bmatrix} \]
04
Compare with Result Vector
The result of our multiplication is \( \begin{bmatrix} -1 \ 6 \end{bmatrix} \), which matches the right-hand side of the system of equations. This confirms that the solution given by \( A \) satisfies both equations.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
System of Equations
A system of equations is a collection of two or more equations with the same set of variables. In this example, we have the system:
Understanding systems of equations is crucial in various fields such as engineering, physics, and economics, where multiple conditions must be met simultaneously.
- Equation 1: \( 3x - 2y = -1 \)
- Equation 2: \( 4x + y = 6 \)
Understanding systems of equations is crucial in various fields such as engineering, physics, and economics, where multiple conditions must be met simultaneously.
Solution Vector
The solution vector is a column matrix that contains the values of the variables that satisfy the system of equations. In this problem, the matrix \( A = \begin{bmatrix} 1 \ 2 \end{bmatrix} \) is deemed as a potential solution vector.The entries in a solution vector represent potential values of the variables (here \(x = 1\) and \(y = 2\)). To verify if a solution vector is valid, we multiply it with the coefficient matrix and compare the result with the original equations' outcomes.
Using a solution vector simplifies the checking process, as it allows for a clean mathematical verification through matrix operations.
Using a solution vector simplifies the checking process, as it allows for a clean mathematical verification through matrix operations.
Coefficient Matrix
A coefficient matrix is a matrix composed of the coefficients of the variables in a system of equations. For example, for the system:
- \( 3x - 2y = -1 \)
- \( 4x + y = 6 \)
Matrix Operations
Matrix operations are procedures that can manipulate matrices to solve equations or transform data. The primary operation here is matrix multiplication, which is used to determine if a given vector is a solution to a system of equations.Matrix multiplication involves taking a row from the first matrix (the coefficient matrix) and a column from the second matrix (the solution vector or any other matrix) and performing element-wise multiplication followed by a summation of the results. For example, to check our solution vector,Perform:\[\begin{bmatrix} 3 & -2 \ 4 & 1 \end{bmatrix} \begin{bmatrix} 1 \ 2 \end{bmatrix} = \begin{bmatrix} 3(1) + (-2)(2) \ 4(1) + 1(2) \end{bmatrix} = \begin{bmatrix} -1 \ 6 \end{bmatrix}\]This operation confirms the solution. Matrix operations are essential tools in linear algebra and are foundational for solving systems of linear equations in a structured and efficient manner.