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Published on: 02/11/2025
Download CBSE Class 12th Standard CBSE Maths question papers, sample papers, important questions, and previous year solved papers in PDF format. Get free study materials, NCERT solutions, and exam preparation resources for Class 12th Standard CBSE Maths
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1.
If \(A=\left[\begin{array}{lll}2 & -3 & 4\end{array}\right], B=\left[\begin{array}{l}3 \\ 2 \\ 2\end{array}\right], X=\left[\begin{array}{lll}1 & 2 & 3\end{array}\right]\) and \(Y=\left[\begin{array}{l}2 \\ 3 \\ 4\end{array}\right]\), then AB+XY is equal to
[28]
[24]
28
24
2.
Given that matrices A and B are of order \(3 \times n\) and \(m \times 5\) respectively, then the order of matrix C = 5A + 3B is
3 x 5 and m = n
3 x 5
3 x 3
5 x 5
3.
Given that \(A=\left[\begin{array}{cc}\alpha & \beta \\ \gamma & -\alpha\end{array}\right]\) and \(A^2=3 I\), then
\(1+\alpha^2+\beta \gamma=0 \)
\(1-\alpha^2-\beta \gamma=0 \)
\(3-\alpha^2-\beta \gamma=0 \)
\(3+\alpha^2+\beta \gamma=0\)
4.
If A is a square matrix such that A²=A, then (I + A)3 – 7A is
A
I + A
I - A
I
5.
If \(A=\left[\begin{array}{cc}0 & 2 \\ 3 & -4\end{array}\right]\) and \(k A=\left[\begin{array}{cc}0 & 3 a \\ 2 b & 24\end{array}\right]\), then the value of k, a and b respectively, are
-6,-12,-18
-6,-4,-9
-6,4,9
-6,12,18
6.
A matrix \(A=\left[a_{i j}\right]_{3 \times 3}\) is defined by \(a_{i j}=\left\{\begin{array}{cl}2 i+3 j, & i<j \\ 5, & i=j . \\ 3 i-2 j, & i>j\end{array}\right.\) The number of elements in A which are more than 5 , is
3
4
5
6
7.
If \(\left[\begin{array}{cc}2 a+b & a-2 b \\ 5 c-d & 4 c+3 d\end{array}\right]=\left[\begin{array}{cc}4 & -3 \\ 11 & 24\end{array}\right]\), then the value of a+b-c+2d is
8
10
4
-8
8.
If \(A=\left[a_{i j}\right]\) is a square matrix of order 2 such that \(a_{i j}=\left\{\begin{array}{ll}1, & \text { when } i \neq j \\ 0, & \text { when } i=j\end{array}\right.\), then \(A^2\) is
\(\left[\begin{array}{ll}1 & 0 \\ 1 & 0\end{array}\right]\)
\(\left[\begin{array}{ll}1 & 1 \\ 0 & 0\end{array}\right]\)
\(\left[\begin{array}{ll}1 & 1 \\ 1 & 0\end{array}\right]\)
\(\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right] \)
9.
If \(A=\left[\begin{array}{ll}1 & 0 \\ 2 & 1\end{array}\right], B=\left[\begin{array}{ll}x & 0 \\ 1 & 1\end{array}\right]\) and \(A=B^2\), then x equals
\(\pm 1\)
-1
1
2
10.
A and B are square matrices of same order. If (A+B)²= A² + B², then
AB = BA
AB =-BA
AB = 0
BA = 0
11.
If \(A=\left[\begin{array}{ll}3 & 4 \\ 5 & 2\end{array}\right]\) and 2 A+B is a null matrix, then B is equal to
\(\left[\begin{array}{cc}6 & 8 \\ 10 & 4\end{array}\right]\)
\(\left[\begin{array}{cc}-6 & -8 \\ -10 & -4\end{array}\right]\)
\(\left[\begin{array}{cc}5 & 8 \\ 10 & 3\end{array}\right]\)
\(\left[\begin{array}{cc}-5 & -8 \\ -10 & -3\end{array}\right]\)
12.
If \(x\left[\begin{array}{l}1 \\ 2\end{array}\right]+y\left[\begin{array}{l}2 \\ 5\end{array}\right]=\left[\begin{array}{l}4 \\ 9\end{array}\right]\), then
x = 1, y = 2
x = 2, y = 1
x = 1, y = -1
x = 3, y = 2
13.
If \(A=\left[\begin{array}{ll} x & 0 \\ 1 & 1 \end{array}\right]\) and \(B=\left[\begin{array}{cc} 4 & 0 \\ -1 & 1 \end{array}\right]\) then the value of x for which A2 = B is
-2
2
2 or -2
4
14.
For the matrix A = \(\left[\begin{array}{ccc} 2 & -1 & 1 \\ \lambda & 2 & 0 \\ 1 & -2 & 3 \end{array}\right]\) to be invertible, the value of \(\lambda\) is
0
10
R - {10}
R - {-10}
15.
The product of matrix P and Q is equal to a diagonal matrix. If the order of matrix Q is 3 \(\times\) 2, then the order of matrix P is
2 \(\times\) 2
3 \(\times\) 3
2 \(\times\) 3
3 \(\times\) 2
16.
lf A is a square matrix of order 2 and |A| = -2, then value of |5A'| is
-50
-10
10
50
17.
Find the matrix A2, where A = [aij] is a 2 \(\times\) 2 matrix whose elements are given by
aij = maximum (i, j) - minimum (i, j)
\(\left[\begin{array}{ll} 0 & 0 \\ 0 & 0 \end{array}\right]\)
\(\left[\begin{array}{ll} 0 & 1 \\ 1 & 0 \end{array}\right]\)
\(\left[\begin{array}{ll} 1 & 0 \\ 0 & 1 \end{array}\right]\)
\(\left[\begin{array}{ll} 1 & 1 \\ 1 & 1 \end{array}\right]\)
18.
If [x 2 0] \(\left[\begin{array}{c} 5 \\ -1 \\ x \end{array}\right]\)=[3 1] \(\left[\begin{array}{c} -2 \\ x \end{array}\right]\), then value of x is
-1
0
1
2
19.
If inverse of matrix \(\left[\begin{array}{ccc} 7 & -3 & -3 \\ -1 & 1 & 0 \\ -1 & 0 & 1 \end{array}\right]\)is the matrix \(\left[\begin{array}{lll} 1 & 3 & 3 \\ 1 & \lambda & 3 \\ 1 & 3 & 4 \end{array}\right]\), then the value of \(\lambda\) is
-4
1
3
4
20.
If A is a square matrix of order 3 such that the value of | adj A | = 8, then the value of |4T | is
\(\sqrt{2}\)
-\(\sqrt{2}\)
8
2\(\sqrt{2}\)
21.
If A = \(\left[\begin{array}{ccc} a & c & -1 \\ b & 0 & 5 \\ 1 & -5 & 0 \end{array}\right]\) is a skew-symmetric matrix, then the value of 2a - (b + c) is
0
1
-10
10
22.
If \(A=\left[\begin{array}{ll} 3 & -2 \\ 4 & -2 \end{array}\right]\) then the value of kif, A2 = kA - 2I is
0
8
-7
1
23.
The matrix \(\left[\begin{array}{rrr} 2 & -1 & 4 \\ 1 & 0 & -5 \\ -4 & 5 & 7 \end{array}\right]\) is
a symmetric matrix
a skew-symmetric matrix
a diagonal matrix
none of these
24.
If matrix A is of order m x n, and for matrix B, AB and BA both are defined, then order of matrix B is
m x n
n x n
n x n
n x m
25.
A matrix has 18 elements, then possible number of orders of a matrix are
3
4
6
5
26.
If \(A=\left[\begin{array}{rr} 3 & 1 \\ -1 & 2 \end{array}\right]\) then A2 - 5A - 7I iS
a zero matrix
an identity matrix
diagonal matrix
none of these
27.
If \(A=\left[\begin{array}{lll} 0 & 0 & 1 \\ 0 & 1 & 0 \\ 1 & 0 & 0 \end{array}\right]\) then A6 is equal to
zero matrix
A
I
none of these
28.
The matrix A satisfies the equation \(\left[\begin{array}{rr} 0 & 2 \\ -1 & 1 \end{array}\right] A=\left[\begin{array}{ll} 1 & 0 \\ 0 & 1 \end{array}\right]\) then matrix A is
\(\left[\begin{array}{rr} 2 & 0 \\ 1 & -1 \end{array}\right]\)
\(\left[\begin{array}{rr} 1 & -2 \\ 1 & 0 \end{array}\right]\)
\(\left[\begin{array}{cc} \frac{1}{2} & -1 \\ \frac{1}{2} & 0 \end{array}\right]\)
\(\left[\begin{array}{rr} 1 & 2 \\ -1 & 0 \end{array}\right]\)
29.
If \(F(x)=\left[\begin{array}{rr} \cos x & \sin x \\ -\sin x & \cos x \end{array}\right] \text { , }\) then F(x) F(y) is equal to
F(x)
F(xy)
F(x + y)
F(x - y)
30.
If A and B are symmetric matrices of same order, then (AB' - BA') is a
skew-symmetric matrix
null matrix
symmetric matrix
unit matrix
31.
For any two matrices A and B, we have
AB=BA
AB ≠BA
AB = 0
None of these
32.
The value of x such that
\(\left[\begin{array}{lll}
1 & 2 & 1
\end{array}\right]\left[\begin{array}{lll}
1 & 2 & 0 \\
2 & 0 & 1 \\
1 & 0 & 2
\end{array}\right]\left[\begin{array}{l}
0 \\
2 \\
x
\end{array}\right]=O, \mathrm{i}\)
1
0
-1
3
33.
If matrix \(A=\left[a_{i j}\right]_{2 \times 2},\ where \ a_{i j}=\left\{\begin{array}{l}1, \text { if } i \neq j \\ 0, \text { if } i=j\end{array}\right.\) Then \(A^{2}\) is equal to
I
A
0
None ofthese
34.
If \(\left[\begin{array}{cc}2 x+y & 4 x \\ 5 x-7 & 4 x\end{array}\right]=\left[\begin{array}{cc}7 & 7 y-13 \\ y & x+6\end{array}\right]\), then
x = 3, y = 1
x = 2, y = 3
x = 2, y = 4
x = 3, y = 3
35.
If A and B are square matrices of the same order and AB = 3I,then A-1 is equal to
3B
\(\frac{1}{3}B\)
3B-1
\(\frac{1}{3}B^{-1}\)
36.
Matrices A and B will be inverse of each other only if
AB = BA
AB = BA = 0
AB = 0,
AB = BA = I
37.
If X, A and B are matrices of the same order such that X = AB, then we apply elementary row transformations simultaneously on X and on the matrix
B
A
AB
Both A and B
38.
On using elementary row operation \(R_{1} \rightarrow R_{1}-3 R_{2}\) in the following matrix equation \(\left[\begin{array}{ll}4 & 2 \\ 3 & 3\end{array}\right]=\left[\begin{array}{ll}1 & 2 \\ 0 & 3\end{array}\right]\left[\begin{array}{ll}2 & 0 \\ 1 & 1\end{array}\right],\) we have
\(\left[\begin{array}{cc}-5 & -7 \\ 3 & 3\end{array}\right]=\left[\begin{array}{cc}1-7 \\ 0 & 3\end{array}\right]\left[\begin{array}{ll}2 & 0 \\ 1 & 1\end{array}\right]\)
\(\left[\begin{array}{cc}-5 & -7 \\ 3 & 3\end{array}\right]=\left[\begin{array}{cc}1 & 2 \\ 0 & 3\end{array}\right]\left[\begin{array}{cc}-1 & -3 \\ 1 & 1\end{array}\right]\)
\(\left[\begin{array}{cc}-5 & -7 \\ 3 & 3\end{array}\right]=\left[\begin{array}{cc}1 & 2 \\ 1 & -7\end{array}\right]\left[\begin{array}{ll}2 & 0 \\ 1 & 1\end{array}\right]\)
\(\left[\begin{array}{rr}4 & 2 \\ -5 & -7\end{array}\right]=\left[\begin{array}{cc}1 & 2 \\ -3 & -3\end{array}\right]\left[\begin{array}{ll}2 & 0 \\ 1 & 1\end{array}\right]\)
39.
On using elementary column operations \(C_{2} \rightarrow C_{2}-2 C_{1}\) in the following matrix equation \(\left[\begin{array}{cc}1 & -3 \\ 2 & 4\end{array}\right]=\left[\begin{array}{cc}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{ll}3 & 1 \\ 2 & 4\end{array}\right]\), we have
\(\left[\begin{array}{cc}1 & -5 \\ 0 & 4\end{array}\right]=\left[\begin{array}{cc}1 & -1 \\ -2 & 2\end{array}\right]\left[\begin{array}{cc}3 & -5 \\ 2 & 0\end{array}\right]\)
\(\left[\begin{array}{cc}1 & -5 \\ 0 & 4\end{array}\right]=\left[\begin{array}{cc}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{cc}3 & -5 \\ -0 & 2\end{array}\right]\)
\(\left[\begin{array}{cc}1 & -5 \\ 2 & 0\end{array}\right]=\left[\begin{array}{cc}1 & -3 \\ 0 & 1\end{array}\right]\left[\begin{array}{cc}3 & 1 \\ -2 & 4\end{array}\right]\)
\(\left[\begin{array}{cc}1 & -5 \\ 2 & 0\end{array}\right]=\left[\begin{array}{cc}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{cc}3 & -5 \\ 2 & 0\end{array}\right]\)
40.
On usiig elementary column operations C2➝ C2 - 2C1 in the following matrix equation\(\left[\begin{array}{cc} 1 & -3 \\ 2 & 4 \end{array}\right]=\left[\begin{array}{cc} 1 & -1 \\ 0 & 1 \end{array}\right]\left[\begin{array}{cc} 3 & 1 \\ 2 & 4 \end{array}\right]\) ,we have
\(\left[\begin{array}{cc} 1 & -5 \\ 0 & 4 \end{array}\right]=\left[\begin{array}{cc} 1 & -1 \\ -2 & 2 \end{array}\right]\left[\begin{array}{cc} 3 & -5 \\ 2 & 0 \end{array}\right]\)
\(\left[\begin{array}{cc}1 & -5 \\ 0 & 4\end{array}\right]=\left[\begin{array}{cc}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{cc}3 & -5 \\ -0 & 2\end{array}\right]\)
\(\left[\begin{array}{cc}1 & -5 \\ 2 & 0\end{array}\right]=\left[\begin{array}{cc}1 & -3 \\ 0 & 1\end{array}\right]\left[\begin{array}{cc}3 & 1 \\ -2 & 4\end{array}\right]\)
\(\left[\begin{array}{cc}1 & -5 \\ 2 & 0\end{array}\right]=\left[\begin{array}{cc}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{cc}3 & -5 \\ 2 & 0\end{array}\right]\)
41.
The matrix \(\left[\begin{array}{ccc}0 & -5 & 8 \\ 5 & 0 & 12 \\ -8 & -12 & 0\end{array}\right]\) is a
diagonal matrix
symmetric matrix
skew-symmetric matrix
scalar matrix
42.
\(A=\left[\begin{array}{cc}\cos \alpha & -\sin \alpha \\ \sin \alpha & \cos \alpha\end{array}\right]\), then if the value of \(\alpha\) is
\(\frac{\pi}{6}\)
\(\frac{\pi}{3}\)
\(\frac{3 \pi}{2}\)
\(\pi\)
43.
The set of all 2x 2 matrices which is commutative with the matrix.\(\left[\begin{array}{ll} 1 & 1 \\ 1 & 0 \end{array}\right]\) with respect to matrix multiplication is
\(\left[\begin{array}{ll} p & q \\ r & r \end{array}\right]\)
\(\left[\begin{array}{ll} p & q \\ q & r \end{array}\right]\)
\(\left[\begin{array}{cc} p-q & p \\ q & r \end{array}\right]\)
\(\left[\begin{array}{cc} p & q \\ q & p-q \end{array}\right]\)
44.
If A and B are square matrices of the sameorder, then (A + B) (A - B) is equal to
A2-B2
A2 - BA - AB - B2
A2 - B2 + BA - AB
A2 - BA + B2 + AB
45.
If \(A=\left[\begin{array}{ccc} 2 & -1 & 3 \\ -4 & 5 & 1 \end{array}\right] \text { and } B=\left[\begin{array}{cc} 2 & 3 \\ 4 & -2 \\ 1 & 5 \end{array}\right] \text { , then }\)
only AB is defined
only BA is defined
AB and BA both are defined
AB and BA both are not defined
46.
If the product of two matrices is a zero matrix, then
atleast one of the matrix is a zero matrix
both the matrices are zero matrices
it is not necessary that one of the matrices is a zero matrix
None of the above
47.
The product \(\left[\begin{array}{rr} a & b \\ -b & a \end{array}\right]\left[\begin{array}{rr} a & -b \\ b & a \end{array}\right]\) is equal to
\(\left[\begin{array}{cc}a^{2}+b^{2} & 0 \\ 0 & a^{2}+b^{2}\end{array}\right]\)
\(\left[\begin{array}{ll}(a+b)^{2} & 0 \\ (a+b)^{2} & 0\end{array}\right]\)
\(\left[\begin{array}{ll}a^{2}+b^{2} & 0 \\ a^{2}+b^{2} & 0\end{array}\right]\)
\(\left[\begin{array}{ll}a & 0 \\ 0 & b\end{array}\right]\)
48.
If A and B are two matrices of the order \(3 \times m\) and \(3 \times n\) respectively and m=n, then the order of the matrix \((5 A-2 B)\) is
m x 3
3 x 3
m x n
3 x n
49.
If \(\left[\begin{array}{rr}1 & 2 \\ -2 & -b\end{array}\right]+\left[\begin{array}{ll}a & 4 \\ 3 & 2\end{array}\right]=\left[\begin{array}{ll}5 & 6 \\ 1 & 0\end{array}\right]\), then \(a^{2}+b^{2}\) is equal to
20
22
12
10
50.
1f If \(A=\left[\begin{array}{ll}2 & 3 \\ 1 & 2\end{array}\right], B=\left[\begin{array}{lll}1 & 3 & 2 \\ 4 & 3 & 1\end{array}\right], C=\left[\begin{array}{l}1 \\ 2\end{array}\right]\) and \(D=\left[\begin{array}{lll}4 & 6 & 8 \\ 5 & 7 & 9\end{array}\right]\), then which of the following is defined?
A + B
B + C
C + D
B + D
51.
Which of the given values of x and y make the following pair of matrices equal \(\left[\begin{array}{cc} 3 x+7 & 5 \\ y+1 & 2-3 x \end{array}\right]\left[\begin{array}{cc} 0 & y-2 \\ 8 & 4 \end{array}\right] ?\)
\(x=\frac{-1}{3}, y=7\)
not possible to find
\(y=7, x=\frac{-2}{3}\)
\(x=\frac{-1}{3}, y=\frac{-2}{3}\)
52.
The matrix \(P=\left[\begin{array}{lll} 0 & 0 & 4 \\ 0 & 4 & 0 \\ 4 & 0 & 0 \end{array}\right]\) is not A.
square matrix
diagonal matrix
unit matrix
None of these
53.
Total number of possible matrices of order 3 x 3 with each entry 2 or 0 is
9
27
81
512
54.
If a matrix has 8 elements, then which of the following will not be a possible order of the matrix?
1x 8
2 x 4
4x2
4 x 4
55.
If A is a 3 x 2 matrix, B is a 3 x 3 matrix and Cis a 2 x 3 matrix, then the elements in A, Band C are respectively
6,9,8
6,9,6
9,6,6
6,6,9
56.
To construct a 2 x 3 matrix [aij], such that aij = – \(\frac { i-3j }{ 4 } \) The values that i and j can take are …….
i = 1, 2, 3 ; j = 1, 2, 3
i = 1, 2 ; j = 1, 2, 3
i = 1, 2 ; j = 1, 2
i = 1, 2, 3 ; j = 1, 2
57.
If, \({ a }_{ ij }=\frac { 1 }{ 2 } |i-3j|\) the value of a22 is
0
-2
2
3
58.
What is the element in the 2nd row and 1st column of a 2 x 2 Matrix A= [ aij], such that a = (i + 3) (j – 1)
0
4
-5
5
59.
\(\left[ \begin{matrix} 2 & 3 & 1 \\ 1 & 2 & 4 \end{matrix}\begin{matrix} 5 & 1 \\ 2 & 2 \end{matrix} \right] \) is a matrix of order
2 x 5
2 x 2
5 x 2
5 x 5
60.
\(\begin{bmatrix} 3 & 0 \\ 0 & 4 \end{bmatrix}\) is example of
an identity matrix
a zero matrix.
a Scalar m
diagonal matrix.
61.
Consider the following information regarding the number of men and women workers in three BPOs I, II and III
| Men | Women | |
| I | 35 | 20 |
| II | 20 | 23 |
| III | 25 | 25 |
What does the entry in the second row and first column represent if the information is represented as a 3 x 2 matrix?
The number of Men in BPO II
The number of Women in BPO II
The number of Women in BPO I
The number of Men in BPO I
62.
[5] is a scalar matrix of order
2
5
0
1
63.
For what real value of y will matrix A be equal to matrix B, where
\(A=\begin{bmatrix} 3x-4 & 5y \\ 8 & { y }^{ 2 }-4y \end{bmatrix};B=\begin{bmatrix} x+1 & 6{ y }^{ 2 }+1 \\ 8 & -3 \end{bmatrix}\)
1, 3
No real value
1/3, 1/2
2 and 3
64.
\(\begin{bmatrix} 2 & 4 \\ 1 & 3 \end{bmatrix}\) is a matrix of order
1
4
2
3
65.
\(\begin{bmatrix} x+10 & { y }^{ 2 }+2y \\ 0 & -4 \end{bmatrix} =\begin{bmatrix} 3x+4 & 3 \\ 0 & { y }^{ 2 }-5y \end{bmatrix}\) Then the value of x is ________
6
3
2
0
66.
If A is square matrix such that A2 = A, then (I + A)³ – 7 A is equal to
A
I – A
I
3A
67.
If the matrix A is both symmetric and skew symmetric, then
A is a diagonal matrix
A is a zero matrix
A is a square matrix
None of these
68.
If A = \(\begin{bmatrix} \alpha & \beta \\ \gamma & -\alpha \end{bmatrix}\) is such that A² = I, then
1 + α² + βγ = 0
1 - α² + βγ = 0
1 - α² - βγ = 0
1 + α² - βγ = 0
69.
If A = \(\begin{bmatrix} cos\alpha & -sin\alpha \\ sin\alpha & cos\alpha \end{bmatrix}\), and A + A' = I, then the value of a is
\(\frac { \pi }{ 6 } \)
\(\frac { \pi }{ 6 } \)
\(\pi \)
\(\frac { 3\pi }{ 2 } \)
70.
Assume X, Y, Z, W and P are matrices of order 2 × n, 3 × k, 2 × p, n × 3 and p × k, respectively.
If n = p, then the order of the matrix 7X – 5Z is:
p × 2
2 × n
n × 3
p × n
71.
Assume X, Y, Z, W and P are matrices of order 2 × n, 3 × k, 2 × p, n × 3 and p × k, respectively.
The restriction on n, k and p so that PY + WY will be defined are:
k = 3, p = n
k is arbitrary, p = 2
p is arbitrary, k = 3
k = 2, p = 3
72.
The number of all possible matrices of order 3 × 3 with each entry
27
18
81
512
73.
A = [aij]m × n\ is a square matrix, if
m < n
m > n
m = n
None of these
74.
If A = \(\begin{bmatrix} 5 & x \\ y & 0 \end{bmatrix}\) and A = A’ then
x = 0, y = 5
x = y
x + y = 5
x – y = 5
75.
The diagonal elements of a skew symmetric matrix are
all zeroes
are all equal to some scalar k(≠ 0)
can be any number
none of these
76.
If A = \(\begin{bmatrix} 0 & 2 \\ 2 & 0 \end{bmatrix}\)
\(\begin{bmatrix} 0 & 2 \\ 2 & 0 \end{bmatrix}\)
\(\begin{bmatrix} 0 & 4 \\ 4 & 0 \end{bmatrix}\)
\(\begin{bmatrix} 4 & 0 \\ 4 & 0 \end{bmatrix}\)
\(\begin{bmatrix} 4 & 0 \\ 0 & 4 \end{bmatrix}\)
77.
If matrices A and B are inverse of each other then
AB = BA
AB = BA = I
AB = BA = 0
AB = 0, BA = I
78.
If A is a square matrix such that A²=A, then (I + A)² – 3A is
I
2A
3I
A
79.
Total number of possible matrices of order 2 × 3 with each entry 1 or 0 is
6
36
32
64
80.
If A = diag(3, -1), then matrix A is
\(\begin{bmatrix} 0 & 3 \\ 0 & -1 \end{bmatrix}\)
\(\begin{bmatrix} -1 & 0 \\ 3 & 0 \end{bmatrix}\)
\(\begin{bmatrix} 3 & 0 \\ 0 & -1 \end{bmatrix}\)
\(\begin{bmatrix} 3 & -1 \\ 0 & 0 \end{bmatrix}\)
81.
If A = [aij] is a 2 × 3 matrix, such that aij = \(\frac { { (-i+2j) }^{ 2 } }{ 5 }.\) Then a23 is ________
\(\frac15\)
\(\frac25\)
\(\frac95\)
\(\frac{16}{5}\)
82.
If a matrix has 6 elements, then number of possible orders of the matrix can be
2
4
3
6
83.
Assertion: Matrix \(\begin{bmatrix}
1& 0& 0\\
0& 3& 0\\
0& 0& 4\\
\end{bmatrix}\) is a diagonal matrix.
Reason: Identity matrix of order 3 is a diagonal matrix.
(a) Both A and R are correct; R is the correct explanation of A
(b) Both A and R are correct; R is not the correct explanation of A
(c) A is correct; R is incorrect
(d) R is correct; A is incorrect
84.
Assertion: The matrix \(A=\begin{bmatrix}
9& 1& 2\\
3& 7& 4\\
\end{bmatrix}\)does not possesses any inverse.
Reason: A is not a square matrix.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
85.
Assertion: The matrix \(A=\begin{bmatrix}
0& -1& -2\\
1& 0& -3\\
2& 3& 0\\
\end{bmatrix}\)is a skew symmetric matrix.
Reason: For the given matrix A we have A' = A.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
86.
Assertion: Let \(A=\begin{bmatrix}
1& 4\\
2& 5\\
4& 7\\
\end{bmatrix}\)and \(B=\begin{bmatrix}
4& 3& 6\\
7& 8& 9\\
5& 1& 2\\
\end{bmatrix}\), then the product of the matrices A and B is not defined.
Reason: The number of rows in B is not equal to number of columns in A.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
87.
Assertion: If A = \(\begin{bmatrix}
2& 3\\
1& 2\\
\end{bmatrix}\)and B = \(\begin{bmatrix}
2& -3\\
-1& 2\\
\end{bmatrix}\), then B is the inverse of A.
Reason: If A is a square matrix of order m and if there exists another square matrix B of the same order m, such that AB = BA = I, then B is called the inverse of A.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
88.
Assertion: \(\begin{bmatrix}
3& 0& 0\\
0& 4& 0\\
0& 0& 7\\
\end{bmatrix}\) is a diagonal matrix.
Reason: A = [aij] is a square matrix such that aij = 0, \(\forall i\neq j\),then A is called diagonal matrix.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
89.
For any square matrix A with real number entries, consider the following statements.
Assertion: A + A' is a symmetric matrix.
Reason: A - A' is a skew-symmetric matrix.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
90.
Assertion: If \( A=\frac{1}{3}\begin{bmatrix}
1& -2& 2\\
-2& 1& 2\\
-2& -2& -1\\
\end{bmatrix}\), then (AT)A = I
Reason: For any square matrix, A(AT)T = A
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
91.
Assertion: Addition of matrices is an example of binary operation on the set of matrices of the same order.
Reason: Addition of matrix is commutative.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
92.
Assertion: The order of the matrix A is 3 x 5 and that of B is 2 x 3.Then the matrix AB is not possible.
Reason: No. of columns in A is not equal to no. of rows in B.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
93.
Assertion: The possible dimensions of a matrix containing 32 elements is 6.
Reason: The No. of ways of expressing 32 as a product of two positive integers is 6.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
(c) Assertion is correct, reason is incorrect
(d) Assertion is incorrect, reason is correct.
1.
(a)
[28]
2.
(b)
3 x 5
3.
(c)
\(3-\alpha^2-\beta \gamma=0 \)
4.
(d)
I
5.
(b)
-6,-4,-9
6.
(b)
4
7.
(a)
8
8.
(d)
\(\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right] \)
9.
(c)
1
10.
(b)
AB =-BA
11.
(b)
\(\left[\begin{array}{cc}-6 & -8 \\ -10 & -4\end{array}\right]\)
12.
(b)
x = 2, y = 1
13.
(c)
2 or -2
14.
(d)
R - {-10}
15.
(c)
2 \(\times\) 3
16.
(a)
-50
17.
(b)
\(\left[\begin{array}{ll} 0 & 1 \\ 1 & 0 \end{array}\right]\)
18.
(a)
-1
19.
(d)
4
20.
(d)
2\(\sqrt{2}\)
21.
(a)
0
22.
(d)
1
23.
(d)
none of these
24.
(d)
n x m
25.
(c)
6
26.
(c)
diagonal matrix
27.
(c)
I
28.
(c)
\(\left[\begin{array}{cc} \frac{1}{2} & -1 \\ \frac{1}{2} & 0 \end{array}\right]\)
29.
(c)
F(x + y)
30.
(a)
skew-symmetric matrix
31.
(d)
None of these
32.
(c)
-1
33.
(a)
I
34.
(b)
x = 2, y = 3
35.
\( A B=B I\)
\(\Rightarrow \frac{1}{3}(A B)=I\)
\(\Rightarrow A\left(\frac{1}{3} B\right)=I\)
\( A^{-1}=\frac{1}{3} B \)
36.
By definition of invertible matrix
37.
According to rule of elementary row operations, we apply these operations simultaneously on X and on the first matrix A of the product AB on RHS.
38.
Given, \(\left[\begin{array}{ll}4 & 2 \\ 3 & 3\end{array}\right]=\left[\begin{array}{ll}1 & 2 \\ 0 & 3\end{array}\right]\left[\begin{array}{ll}2 & 0 \\ 1 & 1\end{array}\right]\)
On applying \(R_{1} \rightarrow R_{1}-3 R_{2},\) we get
\(\left[\begin{array}{cc} 4-9 & 2-9 \\ 3 & 3 \end{array}\right]=\left[\begin{array}{cc} 1-0 & 2-9 \\ 0 & 3 \end{array}\right]\left[\begin{array}{cc} 2 & 0 \\ 1 & 1 \end{array}\right]\)
\(\Rightarrow\)\(\left[\begin{array}{rr} -5 & -7 \\ 3 & 3 \end{array}\right]=\left[\begin{array}{rr} 1 & -7 \\ 0 & 3 \end{array}\right] \cdot\left[\begin{array}{ll} 2 & 0 \\ 1 & 1 \end{array}\right]\)
39.
Given, \(\left[\begin{array}{rr}1 & -3 \\ 2 & 4\end{array}\right]=\left[\begin{array}{rr}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{ll}3 & 1 \\ 2 & 4\end{array}\right]\)
On applying \(C_{2} \rightarrow C_{2}-2 C_{1},\)
we get \(\left[\begin{array}{rr}1 & -3-2 \\ 2 & 4-4\end{array}\right]=\left[\begin{array}{rr}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{ll}3 & 1-6 \\ 2 & 4-4\end{array}\right]\)
\(\Rightarrow \left[\begin{array}{rr}1 & -5 \\ 2 & 0\end{array}\right]=\left[\begin{array}{rr}1 & -1 \\ 0 & 1\end{array}\right]\left[\begin{array}{rr}3 & -5 \\ 2 & 0\end{array}\right]\)
40.
\(\left[\begin{array}{rr} 1 & -3 \\ 2 & 4 \end{array}\right]=\left[\begin{array}{rr} 1 & -1 \\ 0 & 1 \end{array}\right]\left[\begin{array}{ll} 3 & 1 \\ 2 & 4 \end{array}\right]\)
41.
\(\text { Let } A=\left[\begin{array}{ccc} 0 & -5 & 8 \\ 5 & 0 & 12 \\ -8 & -12 & 0 \end{array}\right] \text { . Then, } A^{\prime}=-A\)
42.
Hint \(A+A^{\prime}=I\)I
\(\Rightarrow\left[\begin{array}{cc}2 \cos \alpha & 0 \\ 0 & 2 \cos \alpha\end{array}\right]=\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]\)
\(\Rightarrow\)\(2 \cos \alpha=1\)
\(\Rightarrow \cos \alpha=\frac{1}{2}\)
\(\Rightarrow \alpha=\frac{\pi}{3}\)
43.
(d)
\(\left[\begin{array}{cc} p & q \\ q & p-q \end{array}\right]\)
44.
(A + B) (A - B) = A(A - B) + B(A - B)
= A2 - AB + BA - B2
45.
Let A = [aij]2 x 3 and B = [bij]3 x 2
Since, number of columns of A = number of rows of B
\(\therefore\) AB is defined
Also, as number of columns of B = number of rows of A.
\(\therefore\) BA is defined.
Hence, both AB and BA are defined.
46.
(c)
it is not necessary that one of the matrices is a zero matrix
47.
(a)
\(\left[\begin{array}{cc}a^{2}+b^{2} & 0 \\ 0 & a^{2}+b^{2}\end{array}\right]\)
48.
Hint The order of SA is 3 x m and 2B is 3 x n, where m = 7L
\(\therefore\) The order of SA - 2B is 3 x m or 3 x 7L
49.
We have, \(\left[\begin{array}{cc}1 & 2 \\ -2 & -b\end{array}\right]+\left[\begin{array}{ll}a & 4 \\ 3 & 2\end{array}\right]=\left[\begin{array}{ll}5 & 6 \\ 1 & 0\end{array}\right]\)
= \(\left[\begin{array}{cc}a+1 & 6 \\ 1 & 2-b\end{array}\right]=\left[\begin{array}{ll}5 & 6 \\ 1 & 0\end{array}\right]\)
\(\Rightarrow\)a + 1 = 5, 2 - b = 0
\(\Rightarrow\)a = 4, b = 2
\(\Rightarrow\)\(a^{2}+b^{2}=20\)
50.
Only B + D is defined because matrices of the same order can only be added
51.
(b)
not possible to find
52.
If square matrix in which all diagonals elements are 1 and rest are 0, is called unit matrix.
53.
Number of entries in 3 x 3 matrix is 9. Since, each entry has 2 choices, namely 2 or 0. Therefore, number of
\(\text { possible matrices }=\underbrace{2 \times 2 \times 2 \ldots \times 2=2^{9}}_{9 \text { times }}=512\)
54.
We know that if a matrix is of order m x n, then it has mn elements. Thus, to find all possible orders of a matrix with 8 elements, we will find all ordered pairs of natural numbers, whose product is 8. Thus, all possible ordered pair are (1,8), (8, I), (2, 4), (4, 2).
55.
The number of elements in m x n matrix is equal to mn.
56.
(b)
i = 1, 2 ; j = 1, 2, 3
57.
(b)
-2
58.
(a)
0
59.
(a)
2 x 5
60.
(d)
diagonal matrix.
61.
(a)
The number of Men in BPO II
62.
(d)
1
63.
(b)
No real value
64.
(c)
2
65.
(b)
3
66.
(c)
I
67.
(b)
A is a zero matrix
68.
(c)
1 - α² - βγ = 0
69.
(b)
\(\frac { \pi }{ 6 } \)
70.
(b)
2 × n
71.
(a)
k = 3, p = n
72.
(d)
512
73.
(c)
m = n
74.
As \(\begin{bmatrix} 5 & x \\ y & 0 \end{bmatrix}=\begin{bmatrix} 5 & x \\ y & 0 \end{bmatrix}\Rightarrow x=y\)
75.
As in skew symmetric matrix, aij = -aji
⇒ aii = – aii
⇒ 2aii = 0
⇒ aii = 0, i.e. diagonal elements are zeroes.
76.
As A2 = \(\begin{bmatrix} 0 & 2 \\ 2 & 0 \end{bmatrix}+\begin{bmatrix} 0 & 2 \\ 2 & 0 \end{bmatrix}=\begin{bmatrix} 0 & 4 \\ 4 & 0 \end{bmatrix}\)
77.
By definition.
78.
(a)
I
79.
As total elements are 6 and each entry can be done in 2 ways. Hence, total possibilities = 26 = 64.
80.
As diag (3, -1) is a diagonal matrix. Its order is 2 × 2 with diagonal elements 3 and (-1).
81.
As a23 = \(\frac { { (-2+6) }^{ 2 } }{ 5 } =\frac { 16 }{ 5 } \)
82.
As 6 → 1 × 6, 2 × 3, 3 × 2, 6 × 1.
83.
(b) Both A and R are correct; R is not the correct explanation of A
84.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
85.
(c) Assertion is correct, reason is incorrect
86.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
87.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
88.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
89.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
90.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
91.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
92.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
93.
(c) Assertion is correct, reason is incorrect
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