Math Problem Statement

If A and B are invertible, express [(AB) −1 ] T with A−1 and B−1 .

Solution

Given that AA and BB are invertible matrices, we want to express ((AB)1)T\left( (AB)^{-1} \right)^T in terms of A1A^{-1} and B1B^{-1}.

Steps:

  1. Matrix Inversion Property:

    • The inverse of a product of matrices follows the rule: (AB)1=B1A1(AB)^{-1} = B^{-1}A^{-1} This means that the inverse of a product is the reverse product of the inverses.
  2. Transpose of a Matrix:

    • The transpose of a product of matrices follows the rule: (AB)T=BTAT(AB)^T = B^T A^T However, we need the transpose of the inverse, not just the product.
  3. Transpose of an Inverse:

    • The transpose of the inverse of a matrix is the inverse of the transpose: ((AB)1)T=(B1A1)T\left( (AB)^{-1} \right)^T = \left( B^{-1}A^{-1} \right)^T By the property of the transpose of a product, we reverse the order of the matrices: (B1A1)T=(A1)T(B1)T\left( B^{-1}A^{-1} \right)^T = (A^{-1})^T (B^{-1})^T

Final Expression:

((AB)1)T=(A1)T(B1)T\left( (AB)^{-1} \right)^T = (A^{-1})^T (B^{-1})^T

Would you like more details on the matrix properties used here or have any questions?


Here are some related questions:

  1. What is the inverse of a transpose for a general matrix?
  2. How do the determinant and transpose properties relate for invertible matrices?
  3. How do we calculate the inverse of a matrix step-by-step?
  4. What is the property of transposes when applied to sums of matrices?
  5. Can a non-square matrix have an inverse or a transpose?

Tip: The inverse of a product reverses the order of the factors; be mindful of this when dealing with multiple matrices.

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Math Problem Analysis

Mathematical Concepts

Linear Algebra
Matrix Inversion
Matrix Transpose

Formulas

(AB)^{-1} = B^{-1}A^{-1}
(AB)^T = B^T A^T
(A^{-1})^T = (A^T)^{-1}

Theorems

Inverse of a product of matrices
Transpose of a product of matrices
Transpose of an inverse matrix

Suitable Grade Level

College level (Linear Algebra)