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Ch. 6 - Matrices and Determinants
Blitzer - College Algebra 8th Edition
Blitzer8th EditionCollege AlgebraISBN: 9780136970514Not the one you use?Change textbook
All textbooksBlitzer 8th EditionCh. 6 - Matrices and DeterminantsProblem 33ab
Chapter 7, Problem 33ab

In Exercises 27 - 36, find (if possible) the following matrices: a. AB b. BA 4 2 2 3 4 A = 6 1 B = 3 5 - 1 - 2 0
Matrices A and B for exercises in college algebra, chapter on systems of equations.

Verified step by step guidance
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Step 1: Identify the dimensions of matrices A and B. Matrix A is a 3x2 matrix (3 rows, 2 columns), and matrix B is a 2x3 matrix (2 rows, 3 columns).
Step 2: To find the product AB, check if the number of columns in A equals the number of rows in B. Since A is 3x2 and B is 2x3, the product AB is defined and will result in a 3x3 matrix.
Step 3: To find the product BA, check if the number of columns in B equals the number of rows in A. Since B is 2x3 and A is 3x2, the product BA is defined and will result in a 2x2 matrix.
Step 4: Calculate the product AB by multiplying each row of A by each column of B. For each element in the resulting matrix, use the formula: c_ij = ∑k a_ik b_kj, where i is the row index and j is the column index.
Step 5: Calculate the product BA similarly by multiplying each row of B by each column of A, using the same summation formula for matrix multiplication.

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Key Concepts

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

Matrix Multiplication

Matrix multiplication involves multiplying rows of the first matrix by columns of the second matrix and summing the products. The element in the ith row and jth column of the product matrix is the dot product of the ith row of the first matrix and the jth column of the second matrix.
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Dimension Compatibility for Multiplication

Two matrices can be multiplied only if the number of columns in the first matrix equals the number of rows in the second. For example, if A is m×n and B is p×q, multiplication AB is defined only if n = p, resulting in an m×q matrix.
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Non-Commutativity of Matrix Multiplication

Matrix multiplication is generally not commutative, meaning AB does not necessarily equal BA. Even if both products are defined, their results can differ in size and values, so both AB and BA must be computed separately.
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Related Practice
Textbook Question

In Exercises 31–36, use the alternative method for evaluating third-order determinants on here to evaluate each determinant. ∣1561451910∣\(\begin{vmatrix}\)1 & 5 & 6 \\1 & 4 & 5 \\1 & 9 & 10\(\end{vmatrix}\)

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Textbook Question

Write each matrix equation as a system of linear equations without matrices.

[20−1030110][xyz]=[695]\(\begin{bmatrix}\)2 & 0 & -1 \\0 & 3 & 0 \\1 & 1 & 0\(\end{bmatrix}\[\begin{bmatrix}\)x \(\y\) \(\z\]\end{bmatrix}\)=\(\begin{bmatrix}\)6 \\9 \\5\(\end{bmatrix}\)

Textbook Question

In Exercises 31–36, use the alternative method for evaluating third-order determinants on here to evaluate each determinant. ∣0.5750.5390.513∣\(\begin{vmatrix}\)0.5 & 7 & 5 \\0.5 & 3 & 9 \\0.5 & 1 & 3\(\end{vmatrix}\)

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Textbook Question

Solve each system of equations using matrices. Use Gaussian elimination with back-substitution or Gauss-Jordan elimination.

{2x+2y+7z=−12x+y+2z=24x+6y+z=15\(\begin{cases}\)2x + 2y + 7z = -1 \\2x + y + 2z = 2 \\4x + 6y + z = 15\(\end{cases}\)

Textbook Question

Solve each system of equations using matrices. Use Gaussian elimination with back-substitution or Gauss-Jordan elimination.

{w+x+y+z=42w+x−2y−z=0w−2x−y−2z=−23w+2x+y+3z=4\(\begin{cases}\)w + x + y + z = 4 \\2w + x - 2y - z = 0 \(\w\) - 2x - y - 2z = -2 \\3w + 2x + y + 3z = 4\(\end{cases}\)

Textbook Question

Write each matrix equation as a system of linear equations without matrices.

[4−72−3][xy]=[−31]\(\begin{bmatrix}\)4 & -7 \\2 & -3\(\end{bmatrix}\[\begin{bmatrix}\)x \(\y\]\end{bmatrix}\)=\(\begin{bmatrix}\)-3 \\1\(\end{bmatrix}\)