Find the inverse, if it exists, for each matrix.[22−4260−3−35]\left[ \begin{matrix} 2 & 2 & -4 \\ 2 & 6 & 0 \\ -3 & -3 & 5 \end{matrix} \right]

Ch. 5 - Systems and Matrices

Lial13th EditionCollege AlgebraISBN: 9780136881063Not the one you use?Change textbook

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Lial 13th Edition

Ch. 5 - Systems and Matrices

Problem 27

Chapter 6, Problem 27

Find the inverse, if it exists, for each matrix. $[\begin{matrix} 2 & 2 & - 4 \\ 2 & 6 & 0 \\ - 3 & - 3 & 5 \end{matrix}]$

Verified step by step guidance

Identify the given 3x3 matrix $ A $ for which you need to find the inverse.

Calculate the determinant of matrix $ A $ using the formula for a 3x3 matrix determinant: $ \det(A) = a(ei - fh) - b(di - fg) + c(dh - eg) $, where the elements of $ A $ are $ \begin{bmatrix} a & b & c \\ d & e & f \\ g & h & i \end{bmatrix} $.

Check if the determinant is nonzero. If $ \det(A) = 0 $, the inverse does not exist. If $ \det(A) \neq 0 $, proceed to find the inverse.

Find the matrix of minors by calculating the determinant of each 2x2 submatrix formed by removing the row and column of each element.

Form the matrix of cofactors by applying a checkerboard pattern of signs (+, -, +, -, +, -, +, -, +) to the matrix of minors, then transpose this matrix to get the adjugate matrix. Finally, multiply the adjugate matrix by $ \frac{1}{\det(A)} $ to obtain the inverse matrix $ A^{-1} $.

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Key Concepts

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

Matrix Inverse

The inverse of a matrix A is another matrix, denoted A⁻¹, such that when multiplied together, they yield the identity matrix. Only square matrices with nonzero determinants have inverses. Finding the inverse is essential for solving matrix equations and understanding linear transformations.

Determinant of a Matrix

The determinant is a scalar value computed from a square matrix that indicates whether the matrix is invertible. If the determinant is zero, the matrix does not have an inverse. For a 3x3 matrix, the determinant is calculated using a specific formula involving minors and cofactors.

Methods for Finding the Inverse

Common methods to find a matrix inverse include the adjoint method, which uses cofactors and the determinant, and row reduction to the identity matrix using elementary row operations. Understanding these methods helps efficiently compute the inverse or determine if it does not exist.

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