Which of the following are correct?
(A) For a square matrix A, if A³ = I, then A⁻¹ = A².
(B) The determinant of only a square matrix can be defined.
(C) If A is a square matrix of order 3, then the number of minors of the matrix A is 3.
(D) If A and B are two non-singular matrices of the same order, then (AB)⁻¹ = B⁻¹A⁻¹.
Choose the correct answer from the options given below:
Which of the following are correct?
(A) For a square matrix A, if A³ = I, then A⁻¹ = A².
(B) The determinant of only a square matrix can be defined.
(C) If A is a square matrix of order 3, then the number of minors of the matrix A is 3.
(D) If A and B are two non-singular matrices of the same order, then (AB)⁻¹ = B⁻¹A⁻¹.
Choose the correct answer from the options given below:
Solution
For statement (A), given that where is the identity matrix.
By the definition of inverse matrix, if , then is the inverse of .
Therefore,
Statement (A) is correct.
For statement (B), determinants are only defined for square matrices where the number of rows equals the number of columns.
A determinant can be found for a or matrix, but cannot be found for a or matrix.
Statement (B) is correct.
For statement (C), a minor is the determinant obtained after removing one row and one column.
For a matrix:
Number of choices for removing a row
Number of choices for removing a column
Total number of minors
Statement (C) is incorrect. The number of minors is 9, not 3.
For statement (D), this is a standard property of matrix inverses.
To verify that :
Statement (D) is correct.
Statements (A), (B), and (D) are correct.
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