/*! This file is auto-generated */ .wp-block-button__link{color:#fff;background-color:#32373c;border-radius:9999px;box-shadow:none;text-decoration:none;padding:calc(.667em + 2px) calc(1.333em + 2px);font-size:1.125em}.wp-block-file__button{background:#32373c;color:#fff;text-decoration:none} Problem 8 In Exercises 1-i6, let $$ A=... [FREE SOLUTION] | 91Ó°ÊÓ

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In Exercises 1-i6, let $$ A=\left[\begin{array}{rrr} -2 & 1 & 3 \\ 4 & 0 & -1 \end{array}\right], \quad B=\left[\begin{array}{rrr} 4 & 1 & -2 \\ 5 & -1 & 3 \end{array}\right], \quad C=\left[\begin{array}{rr} 2 & -1 \\ 0 & 6 \\ -3 & 2 \end{array}\right], \quad \text { and } \quad D=\left[\begin{array}{rr} -4 & 2 \\ 3 & 5 \\ -1 & -3 \end{array}\right] \text {. } $$ Compute the indicated quantity, if it is defined. $$ (C D)^{\tau} $$

Short Answer

Expert verified
The product \( (CD)^{\tau} \) is undefined because \( CD \) cannot be computed.

Step by step solution

01

Check Matrix Dimensions for Multiplication

For matrix multiplication \( CD \) to be defined, the number of columns in matrix \( C \) must equal the number of rows in matrix \( D \). Here, \( C \) is a \(3 \times 2\) matrix, and \( D \) is a \(3 \times 2\) matrix. Since the number of columns in \( C \) (2) does not match the number of rows in \( D \) (3), the multiplication \( CD \) is not defined.

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Key Concepts

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

Matrix Multiplication
Matrix multiplication is a fundamental operation in linear algebra, involving two matrices. It's a process where each element in a row of the first matrix is multiplied by the corresponding element in a column of the second matrix, and then the products are summed to produce an element of the resulting matrix. This operation has specific rules regarding the dimensions of the matrices involved, which determine if the multiplication is possible.

For two matrices to be multiplied, the number of columns in the first matrix must equal the number of rows in the second matrix. If matrix \( A \) has dimensions \( m \times n \) and matrix \( B \) has dimensions \( n \times p \), their product \( AB \) will be an \( m \times p \) matrix.

In the provided exercise, matrix \( C \) is 3 rows by 2 columns, \(3 \times 2\), and matrix \( D \) is also \(3 \times 2\), which means the multiplication \( CD \) is not possible. The inner dimensions (the 2 from \( C \) and the 3 from \( D \)) must be equal for multiplication to be defined. Hence, understanding and checking these dimensions is a critical first step in any matrix multiplication problem.
Matrix Transposition
A matrix transposition is a simple yet powerful operation in linear algebra. It involves switching the rows and columns of a given matrix. This operation results in a new matrix where the rows of the original become the columns of the transposed and vice versa. It is often denoted by the superscript \( \tau \) or by \( ^T \).

For a matrix \( A \), the transposed matrix \( A^{\tau} \) has the property that the element from the \( i^{th} \) row and \( j^{th} \) column of \( A \) moves to the \( j^{th} \) row and \( i^{th} \) column of \( A^{\tau} \). If matrix \( A \) is \( m \times n \), then \( A^{\tau} \) will be \( n \times m \).

Transposing a matrix can be crucial when solving systems of linear equations, finding determinants, or simplifying matrix multiplication. In the given exercise, we see the expression \((CD)^{\tau}\). However, as \( CD \) is undefined, transposing cannot proceed. Understanding when to transpose or its implications can significantly simplify complex matrix operations.
Linear Algebra
Linear algebra is a branch of mathematics that deals with vectors, matrices, and linear transformations. It provides methods for solving systems of linear equations, understanding vector spaces, and performing matrix operations. Practically, linear algebra is foundational in various scientific fields such as computer science, engineering, physics, and economics.

Concepts like matrix multiplication and transposition are essential components of linear algebra. These operations allow you to manipulate and transform data in multidimensional space. Additionally, understanding matrix properties, such as dimensions and compatibility constraints, is crucial in real-world applications, particularly in computational scenarios where matrices are used to represent data or operations.

Linear algebra is not just about performing operations but also understanding their implications. For example, ensuring compatible dimensions before performing matrix operations ensures meaningful results and avoids errors. The exercise highlights a common pitfall in linear algebra—checking dimensional compatibility before proceeding with further matrix operations, such as multiplication or transposition.

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Most popular questions from this chapter

a. Show that the matrix $$ A=\left[\begin{array}{ll} 2 & -3 \\ 5 & -7 \end{array}\right] $$ is invertible. and find its inverse. b. Use the result in (a) to find the solution of the system of equations $$ 2 x_{1}-3 x_{2}=4, \quad 5 x_{1}-7 x_{2}=-3 \text {. } $$

Find all scalars c, if anv exist, such that the given statement is true. Try to do some of these problems without using pencil and paper. The vector \(3 \mathrm{i}-2 \mathrm{j}+c \mathrm{k}\) is in the span of \(\mathbf{i}+2 \mathbf{j}-\mathbf{k}\) and \(\mathbf{j}+3 \mathbf{k}\).

Mark each of the following True or False. a. Every linear system with the same number of equations as unknowns has a unique solution. b. Every linear system with the same number of equations as unknowns has at least one solution. c. A linear system with more equations than unknowns may have an infinite number of solutions. d. A linear system with fewer equations than unknowns may have no solution. e. Every matrix is row equivalent to a unique matrix in row-echelon form. f. Every matrix is row equivalent to a unique matrix in reduced row-echelon form. g. If \([A \mid\) b \(]\) and \([B \mid\) c \(]\) are row-equivalent partitioned matrices, the linear systems \(A \mathrm{x}=\mathrm{b}\) and \(B \mathrm{x}=\mathrm{c}\) have the same solution set. h. A linear system with a square coefficient matrix \(A\) has a unique solution if and only if \(A\) is row equivalent to the identity matrix. i. A linear system with coefficient matrix \(A\) has an infinite number of solutions if and only if \(A\) can be row-reduced to an echelon matrix that includes some column containing no pivot. j. A consistent linear system with coefficient matrix \(A\) has an infinite number of solutions if and only if \(A\) can be row-reduced to an echelon matrix that includes some column containing no pivot.

In Exercises 30-37, describe all possible values for the unknowns \(x_{i}\) so that the matrix equation is valid. \(2\left[\begin{array}{ll}x_{1} & x_{2}\end{array}\right]-\left[\begin{array}{ll}4 & 7\end{array}\right]=\left[\begin{array}{ll}-2 & 11\end{array}\right]\)

In Exercises \(1-17\), let \(\mathrm{u}=[-1,3,4], \mathrm{v}=\) \([2,1,-1]\), aid \(w=[-2,-1,3]\). Find the indicated quantity. The angle between \(u\) and \(v\)

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