These Matrices Class 12 MCQ And Answers are most important for your upcoming examinations including JEE Main & JEE Advanced. These Matrices Class 12 MCQ And Answers will help you to score good marks in your exams by helping you to prepare the concepts better and hence, help you to understand the concepts more clearly.
Matrices Class 12 MCQ And Answers
1. If A = 
then A² – 5A – 7I is
(A) zero matrix
(B) a diagonal matrix
(C) identity matrix
(D) None of these
Answer: a diagonal matrix
2. If A = 
then |2A| =
(A) 2|A|
(B) 4|A|
(C) 8|A|
(D) None of these
Answer: 4|A|
3. 
(A) α = a² + b², β = ab
(B) α = a² + b², β = 2ab
(C) α = a² + b², β = a² – b²
(D) α = 2ab, β = a² + b²
Answer: α = a² + b², β = 2ab
4. If 
then the value of x, y is
(A) 3, 1
(B) 2, 3
(C) 2, 4
(D) 3, 3
Answer: 2, 3
5. If A is a m × n matrix such that AB and BA are both defined, then B is an
(A) m × n matrix
(B) n × m matrix
(C) n × n matrix
(D) m × m matrix
Answer: n × n matrix
6. If AB = A and BA = B, then
(A) B = 1
(B) A = I
(C) A² = A
(D) B² = I
Answer: A² = A
7. A square matrix A = [aij]n×nis called a lower triangular matrix if aij = 0 for
(A) i = j
(B) i < j
(C) i > j
(D) None of these
Answer: i < j
8. The number of all possible matrices of order 3 × 3 with each entry 0 or 1 is
(A) 18
(B) 512
(C) 81
(D) None of these
Answer: 512
9. For any two matrices A and B, we have
(A) AB = BA
(B) AB ≠ BA
(C) AB = 0
(D) None of these
Answer: None of these
10. If A is a square matrix such that A² = I, then (A – I)³ + (A + I)³ – 7A is equal to
(A) A
(B) I – A
(C) I + A
(D) 3 A
Answer: A
11. If A is a matrix of order m × n and B is a matrix such that AB’ and B’A are both defined, then the order of matrix B is
(A) m × m
(B) n × n
(C) n × m
(D) m × n
Answer: m × n
12. If A and B are two matrices of the order 3 × m and 3 × n, respectively, and m = n, then the order of matrix (5A – 2B) is
(A) m × 3
(B) 3 × 3
(C) m × n
(D) 3 × n
Answer: 3 × n
13. For any unit matrix I
(A) I² = I
(B) |I| = 0
(C) |I| = 2
(D) |I| = 5
Answer: I² = I
14. A matrix A = [aij]m×nis said to be skew symmetric if
(A) aij = 0
(B) aij = aji
(C) aij = -aji
(D) aij = 1
Answer: aij = aji
15. If A and B are square matrices then (AB)’ =
(A) B’A’
(B) A’B’
(C) AB’
(D) A’B’
Answer: B’A’
16. Let A be a non-singular matrix of the order 2 × 2 then |A-1|=
(A) |A|
(B) 1/|A|
(C) 0
(D) 1
Answer: 1/|A|
17. If 
= 0, the value of x is
(A) 3
(B) 8
(C) 24
(D) 0
Answer: 8
18. If 
(A) a unit matrix
(B) A
(C) a null matrix
(D) -A
Answer: a unit matrix
19. If A = 
then A + AT= I if the value of x is
(A) π/6
(B) π/3
(C) π
(D) 0
Answer: π/3
20. The matrix 
is
(A) a symmetric matix
(B) a skew-sybtmetric matrix
(C) a diagonal matrix
(D) None of these
Answer: None of these
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