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Match each matrix multiplication with its answer. a. \(\left[\begin{array}{rr}8 & -2 \\ 1 & 9\end{array}\right] \times\left[\begin{array}{rr}3 & 8 \\ -1 & -4\end{array}\right]\) i. \(\left[\begin{array}{rr}26 & 72 \\ -6 & -28\end{array}\right]\) b. \(\left[\begin{array}{rr}24 & -16 \\ -1 & -36\end{array}\right] \times\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]\) ii. \(\left[\begin{array}{r}36 \\ -17\end{array}\right]\) c. \(\left[\begin{array}{rr}6 & 8 \\ -7 & -1\end{array}\right] \times\left[\begin{array}{l}2 \\ 3\end{array}\right]\) iii. \(\left[\begin{array}{cc}24 & -16 \\ -1 & -36\end{array}\right]\)

Short Answer

Expert verified
a = i, b = iii, c = ii.

Step by step solution

01

Multiply Matrix a by Matrix Term

To perform matrix multiplication for option a: \[\left[\begin{array}{rr}8 & -2 \ 1 & 9\end{array}\right] \times \left[\begin{array}{rr}3 & 8 \ -1 & -4\end{array}\right]\]Calculate the resulting elements:- Top-left: \(8 \times 3 + (-2) \times (-1) = 24 + 2 = 26\)- Top-right: \(8 \times 8 + (-2) \times (-4) = 64 + 8 = 72\)- Bottom-left: \(1 \times 3 + 9 \times (-1) = 3 - 9 = -6\)- Bottom-right: \(1 \times 8 + 9 \times (-4) = 8 - 36 = -28\)Thus, matrix a's product is:\[\left[\begin{array}{rr}26 & 72 \ -6 & -28\end{array}\right]\]
02

Multiply Matrix b by Identity Matrix

For option b, multiply by the identity matrix:\[\left[\begin{array}{rr}24 & -16 \ -1 & -36\end{array}\right] \times \left[\begin{array}{ll}1 & 0 \ 0 & 1\end{array}\right]\]Since it is multiplied by an identity matrix, the matrix remains unchanged:\[\left[\begin{array}{rr}24 & -16 \ -1 & -36\end{array}\right]\]
03

Multiply Matrix c by Column Matrix

For option c:\[\left[\begin{array}{rr}6 & 8 \ -7 & -1\end{array}\right] \times \left[\begin{array}{l}2 \ 3\end{array}\right]\]Compute each element of the resulting vector:- Top: \(6 \times 2 + 8 \times 3 = 12 + 24 = 36\)- Bottom: \(-7 \times 2 + (-1) \times 3 = -14 - 3 = -17\)The result is:\[\left[\begin{array}{r}36 \ -17\end{array}\right]\]
04

Match Each Matrix Multiplication with Its Result

Now, based on calculations:- For option a, the result matrix \(\left[\begin{array}{rr}26 & 72 \ -6 & -28\end{array}\right]\) matches with option i.- For option b, the result matrix \(\left[\begin{array}{rr}24 & -16 \ -1 & -36\end{array}\right]\) matches with option iii.- For option c, the result vector \(\left[\begin{array}{r}36 \ -17\end{array}\right]\) matches with option ii.

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Key Concepts

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

Algebra
Algebra is a branch of mathematics that deals with symbols and the rules for manipulating those symbols. In the context of algebra, matrix multiplication is an essential operation where we deal with these symbols in a structured form. Matrices are arrays of numbers that can represent various algebraic equations or transformations. Matrix multiplication itself follows algebraic rules and serves as a pivotal operation for solving linear equations and other mathematical problems.
Unlike regular multiplication, matrix multiplication combines rows of one matrix with columns of another in a specific manner, requiring adherence to rules such as the compatibility of dimensions. Hence, understanding algebra helps us grasp why certain operations like matrix multiplication function and how they lead to calculated solutions.
Matrices
Matrices are one of the core components of linear algebra, a structure made up of rows and columns of numbers. They are usually denoted by uppercase letters such as A, B, or C. Each number in a matrix is called an element.
Matrices come in various sizes, defined by the number of rows and columns. For example, in a 2x2 matrix, there are 2 rows and 2 columns. Matrices can represent a wide range of data or transformations, which is why understanding their structure is essential.
The dimensions of matrices are crucial for performing operations like multiplication, as only matrices with compatible dimensions can be multiplied together. A solid understanding of matrices lays the groundwork for successfully performing and interpreting matrix operations.
Mathematical Operations
Mathematical operations with matrices, particularly multiplication, require following specific steps to achieve accurate results. In a matrix multiplication, each element of the resulting matrix is the sum of products.
- For two matrices to be multiplied, the number of columns in the first matrix must equal the number of rows in the second matrix. - It’s a step-by-step process: take a row from the first matrix and multiply each element by the corresponding element in a column from the second matrix, then sum those products. - Place the calculated value in the corresponding row and column of the resulting matrix.
This operation differs from element-wise multiplication, where each corresponding element is simply multiplied. Matrix multiplication is a vital operation that enables solving complex systems and performing transformations in various fields.
Identity Matrix
The identity matrix is a particular kind of matrix with properties that make it crucial in matrix operations. It is a square matrix with ones on the diagonal from the upper left to the lower right, and zeros elsewhere.
An identity matrix acts like the number 1 in regular multiplication. When it multiplies any matrix, it leaves the other matrix unchanged. For example, multiplying a matrix by the identity matrix results in the same original matrix. This property is because each element in the product is solely influenced by the corresponding element in the original matrix.
Understanding the identity matrix helps in recognizing how it is used to simplify problems and find solutions. It is also essential for understanding matrix inversion, aiding in the comprehending more complex algebraic processes and solutions.

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