Chapter 8: Problem 117
Apply a graphing utility to perform the indicated matrix operations. $$A=\left[\begin{array}{rrrr}1 & 7 & 9 & 2 \\\\-3 & -6 & 15 & 11 \\\0 & 3 & 2 & 5 \\\9 & 8 & -4 & 1\end{array}\right]$$ Find \(A^{-1}\)
Short Answer
Expert verified
Use a graphing utility to find and verify a non-zero determinant; then find and check the inverse matrix \( A^{-1} \).
Step by step solution
01
Determine the Size of Matrix
The given matrix \( A \) is a 4x4 matrix, meaning it has 4 rows and 4 columns.
02
Check if Matrix is Invertible
A square matrix is invertible if its determinant is non-zero. We need to calculate the determinant of matrix \( A \).
03
Calculate Determinant of Matrix A
Using a graphing utility, enter the matrix \( A \) and compute its determinant. Ensure the answer is not zero. If it's non-zero, proceed to find the inverse.
04
Find the Inverse Matrix
Using the same graphing utility, once the determinant is confirmed non-zero, input matrix \( A \) and use the matrix inverse function to find \( A^{-1} \).
05
Verify the Result
Multiply \( A \) by \( A^{-1} \) using the graphing utility. This product should equal the identity matrix \( I \), confirming that \( A^{-1} \) is correct.
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Key Concepts
These are the key concepts you need to understand to accurately answer the question.
Matrix Inversion
Matrix inversion is a crucial concept in linear algebra. It refers to the process of finding a matrix that, when multiplied by the original matrix, yields the identity matrix. This matrix is known as the inverse of the original matrix.When dealing with a square matrix like matrix \( A \) in our problem, the first step in determining if it can be inverted is checking if it is a square matrix of size \( n \times n \). In our example, matrix \( A \) is a 4x4 matrix, making it potentially invertible if its determinant is non-zero.Matrix inversion requires efficient tools or software, especially for larger matrices. A graphing utility can be very helpful, as it simplifies the computations needed to find the inverse. Once the determinant of matrix \( A \) is confirmed to be non-zero, you can use the inverse function available in the graphing utility to determine \( A^{-1} \).
Determinant Calculation
Calculating the determinant is an essential step in matrix operations, particularly when determining if a matrix is invertible. The determinant is a scalar value that provides important insights into a matrix's properties.To determine if the matrix \( A \) in our task is invertible, its determinant must be calculated. The rule is simple: if the determinant is zero, the matrix does not have an inverse; if it's non-zero, the inverse exists.Graphing utilities are potent tools in this regard. They allow you to compute determinants quickly without manual calculation, which can be error-prone for larger matrices. By inputting matrix \( A \) into the utility, you can easily verify its determinant. Once confirmed that it is not zero, you proceed with finding the inverse.
Graphing Utility
A graphing utility is an invaluable digital tool that can perform various mathematical operations, including those involving matrices, in seconds.For our exercise, utilizing a graphing utility greatly simplifies operations like determinant calculation and finding inverses. These utilities often have built-in functions where you can enter your matrix, and they efficiently execute complex calculations at the click of a button.When handling matrix \( A \), input the values into the graphing utility for both determinant calculation and inversion. Most modern graphing calculators, like the TI-84 or similar software, have dedicated matrix functions. By selecting these, you can compute results without extensive manual computation, ensuring accuracy.
Identity Matrix Verification
Identity matrix verification is a crucial step when dealing with matrix inverses. Once you have computed the inverse of a matrix, it is important to verify that it is correct.Typically, verification is done by multiplying the original matrix \( A \) by its inverse \( A^{-1} \). If the operation is accurate, the product will be the identity matrix \( I \). This matrix has the same dimensions as \( A \) and is filled with ones along its diagonal, and zeroes in all other positions.Using a graphing utility, you can easily multiply \( A \) by \( A^{-1} \) and check if the identity matrix is obtained. If the product is indeed \( I \), you have confirmed the accuracy of your calculations.