21. A square matrix A such that … is called an involutory matrix.
A. A^2 = A
B. A^2 = I
C. A^2 = -A
D. A^2 = -I
22. For any square real matrix A, the matrix A -A^t
is:
A. Symmetric
B. Skew Symmetric
C. Hermitian
D. None of these
23. For a complex square matrix A, the matrix A + (A̅)^t
is:
A. Symmetric
B. Skew symmetric
C. Hermitian
D. Skew Hermitian
24. If A is a square matrix over C and A(A̅)^t = 0, then which of the following is true?
A. A = 0
B. At = 0
C. A̅= 0
D. All of these
25. If A is a square matrix and B is left inverse of A, then:
A. B can be right inverse of A
B. B must be right inverse of A
C. B must not be right inverse of A
D. There is no relation between A and B
26. A square matrix, whose inverse exists, is called:
A. Singular
B. Nonsingular
C. Invertible
D. Both B and C
27. If A and B are nonsingular matrices of the same order, then (AB) ̄1equals:
A. AB
B. A^-1B^-1
C. BA
D. B^-1A^-1
28. A matrix obtained by applying an elementary row operation on In is called:
A. Invertible
B. Non Invertible
C. Elementary
D. Secondary
29. Every elementary matrix E is:
A. Singular
B. Nonsingular
C. Non invertible
D. Symmetric
30. A square matrix A of order n is nonsingular if and only if A is row equivalent to:
A. In
B. -In
C. A^2
D. -A
