Table of contents
- 0. Review of Algebra4h 18m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations1h 43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 5m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 22m
- 10. Combinatorics & Probability1h 45m
7. Systems of Equations & Matrices
Determinants and Cramer's Rule
Problem 7
Textbook Question
In Exercises 1 - 12, find the products AB and BA to determine whether B is the multiplicative inverse of A. 0 1 0 0 0 1 A = 0 0 1 B = 1 0 0 1 0 0 0 1 0

Verified step by step guidance1
Step 1: Understand the problem. You are given two matrices A and B, and you need to find the products AB and BA. Then, determine if B is the multiplicative inverse of A. Recall that if B is the inverse of A, then both AB and BA should equal the identity matrix I.
Step 2: Write down the matrices explicitly. Matrix A is and matrix B is .
Step 3: Calculate the product AB. Multiply matrix A by matrix B by taking the dot product of the rows of A with the columns of B. For each element (i,j) in the product matrix, compute the sum of products of corresponding elements from row i of A and column j of B.
Step 4: Calculate the product BA. Similarly, multiply matrix B by matrix A by taking the dot product of the rows of B with the columns of A, following the same procedure as in Step 3.
Step 5: Compare the resulting matrices AB and BA to the identity matrix . If both AB and BA equal the identity matrix, then B is the multiplicative inverse of A; otherwise, it is not.
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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 product AB is defined only if the number of columns in A equals the number of rows in B. This operation is not commutative, meaning AB may not equal BA.
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Multiplicative Inverse of a Matrix
A matrix B is the multiplicative inverse of matrix A if both AB and BA equal the identity matrix. The identity matrix has 1s on the diagonal and 0s elsewhere. Only square matrices with non-zero determinants have inverses.
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Identity Matrix
The identity matrix acts like 1 in matrix multiplication, leaving any matrix unchanged when multiplied. It is a square matrix with 1s on the main diagonal and 0s elsewhere. Verifying if AB and BA equal the identity matrix confirms if B is the inverse of A.
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Related Practice
Textbook Question
Use Cramer's rule to solve each system of equations. If D = 0, then use another methodto determine the solution set. See Examples 5–7. x + 2y + 3z = 4 4x + 3y + 2z = 1 -x - 2y - 3z = 0
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