Table of contents
- 0. Review of Algebra4h 16m
- 1. Equations & Inequalities3h 18m
- 2. Graphs of Equations43m
- 3. Functions2h 17m
- 4. Polynomial Functions1h 44m
- 5. Rational Functions1h 23m
- 6. Exponential & Logarithmic Functions2h 28m
- 7. Systems of Equations & Matrices4h 6m
- 8. Conic Sections2h 23m
- 9. Sequences, Series, & Induction1h 19m
- 10. Combinatorics & Probability1h 45m
7. Systems of Equations & Matrices
Determinants and Cramer's Rule
Problem 13e
Textbook Question
Are the given matrices inverses of each other? (Hint: Check to see whether their products are the identity matrix I↓n.) [3x3 matrix] and [3x3 matrix]
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1
<Step 1: Understand the concept of matrix inverses. Two matrices A and B are inverses of each other if their product, in both orders (AB and BA), results in the identity matrix I.>
<Step 2: Multiply the first matrix by the second matrix. This involves taking the dot product of the rows of the first matrix with the columns of the second matrix.>
<Step 3: Multiply the second matrix by the first matrix. Again, take the dot product of the rows of the second matrix with the columns of the first matrix.>
<Step 4: Check if both products from Steps 2 and 3 result in the identity matrix I, which is a matrix with 1s on the diagonal and 0s elsewhere.>
<Step 5: Conclude whether the matrices are inverses based on whether both products are the identity matrix.>
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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 combining two matrices to produce a third matrix. For two matrices A and B to be multiplied, the number of columns in A must equal the number of rows in B. The resulting matrix's dimensions will be determined by the outer dimensions of the two matrices. This operation is crucial for determining if two matrices are inverses, as their product must yield the identity matrix.
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Identity Matrix
An identity matrix is a square matrix with ones on the diagonal and zeros elsewhere. For a 3x3 identity matrix, it looks like this: [[1, 0, 0], [0, 1, 0], [0, 0, 1]]. The identity matrix acts as a multiplicative identity in matrix algebra, meaning that any matrix multiplied by the identity matrix remains unchanged. To verify if two matrices are inverses, their product must equal the identity matrix.
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Inverse Matrices
Inverse matrices are pairs of matrices that, when multiplied together, yield the identity matrix. For a matrix A, its inverse is denoted as A^-1, and the relationship is expressed as A * A^-1 = I, where I is the identity matrix. Not all matrices have inverses; a matrix must be square and have a non-zero determinant to possess an inverse. Checking if two matrices are inverses involves calculating their product and confirming it equals the identity matrix.
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