If A and B are two invertible matrices, then which of the following statements are correct? (A) $|A^{-1}| = |A|^{-1}$ Choose the correct answer from the options given below: |
(A), (B) and (C) only (A) and (B) only (A), (B) and (D) only (C) and (D) only |
(A) and (B) only |
The correct answer is Option (2) → (A) and (B) only $\textbf{Check each statement carefully}$ $\textbf{(A)}\;|A^{-1}|=|A|^{-1}$ is true because for any invertible matrix, determinant of inverse is reciprocal of determinant. $\textbf{(B)}\;\text{adj}\,A=|A|\;A^{-1}$ is true (standard identity for invertible matrices). $\textbf{(C)}\;(AB)^{-1}=A^{-1}B^{-1}$ is false because correct formula is $\qquad (AB)^{-1}=B^{-1}A^{-1}$ $\textbf{(D)}\;(A+B)^{-1}=A^{-1}+B^{-1}$ is false (this is never generally true). Thus the correct statements are: (A) and (B). |