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Published on: 02/11/2025
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1.
If \(A=\left[\begin{array}{lll}a & 0 & 0 \\ 0 & a & 0 \\ 0 & 0 & a\end{array}\right]\), then \(\operatorname{det}(\operatorname{adj} A)\) equals
\(a^{27}\)
\(a^9\)
\(a^6\)
\(a^2\)
2.
If A is a square matrix of order 3 , such that \(A(\operatorname{adj} A)=10 I\), then \(|\operatorname{adj} A|\) is equal to
1
10
100
10l
3.
If \(A=\left[\begin{array}{ccc}1 & -1 & 0 \\ 2 & 3 & 4 \\ 0 & 1 & 2\end{array}\right]\) and \(B=\left[\begin{array}{ccc}2 & 2 & -4 \\ -4 & 2 & -4 \\ 2 & -1 & 5\end{array}\right]\), then
\(A^{-1}=B\)
\(A^{-1}=6 B\)
\(B^{-1}=B\)
\(B^{-1}=\frac{1}{6} A\)
4.
For \(A=\left[\begin{array}{cc}3 & 1 \\ -1 & 2\end{array}\right]\), then \(14 A^{-1}\) is given by
\(14\left[\begin{array}{cc}2 & -1 \\ 1 & 3\end{array}\right]\)
\(\left[\begin{array}{cc}4 & -2 \\ 2 & 6\end{array}\right]\)
\(2\left[\begin{array}{ll}2 & -1 \\ 1 & -3\end{array}\right]\)
\(2\left[\begin{array}{cc}3 & -1 \\ 1 & 2\end{array}\right]\)
5.
For matrix \(A=\left[\begin{array}{cc}2 & 5 \\ -11 & 7\end{array}\right]\) then \((\operatorname{adj} A)^{\prime}\) is equal to
\(\left[\begin{array}{cc}-2 & -5 \\ 11 & -7\end{array}\right]\)
\(\left[\begin{array}{cc}7 & 5 \\ 11 & 2\end{array}\right]\)
\(\left[\begin{array}{cc}7 & 11 \\ -5 & 2\end{array}\right]\)
\(\left[\begin{array}{cc}7 & -5 \\ 11 & 2\end{array}\right]\)
6.
Given that A is a square matrix of order 3 and |A|=-4, then \(|\operatorname{adj} A|\) is equal to
-4
4
-16
16
7.
If A and B are invertible square matrices of the same order, then which of the following is not correct?
\(adj A=|A| \cdot A^{-1}\)
\(\operatorname{det}\left(A^{-1}\right)=[\operatorname{det}(A)]^{-1}\)
\((A B)^{-1}=B^{-1} A^{-1}\)
\((A+B)^{-1}=B^{-1}+A^{-1}\)
8.
Given that A is a square matrix of order 3 and |A| = -2, then |adj (24)| is equal to
-26
4
-28
28
9.
If for a square matrix A, A2 - A + l = 0, then A-1 equals
A
A + l
l - A
A - l
10.
If for a square matrix A, A² - 3A + 1 = 0 and A-1 = xA + yl, then the value of x + y is
-2
2
3
-3
11.
Let A be a 3 x 3 matrix such that \(|\operatorname{adj} A|=64\). Then, |A| is equal to
8 only
-8 only
64
8 or -8
12.
If \(A(\operatorname{adj} A)=\left[\begin{array}{lll}3 & 0 & 0 \\ 0 & 3 & 0 \\ 0 & 0 & 3\end{array}\right]\) then the value of \(|A|+|\operatorname{adj} A|\) is equal to
12
9
3
27
13.
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
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.
If A is a square matrix of onder 3 such that the value of \(|\operatorname{adj} A|=8\), then the value of |\(\mid A^T|\) is
\(\sqrt{2}\)
\(-\sqrt{2}\)
8
\(2 \sqrt{2}\)
16.
Let \(A=\left[\begin{array}{cc}200 & 50 \\ 10 & 2\end{array}\right]\)and \(B=\left[\begin{array}{cc}50 & 40 \\ 2 & 3\end{array}\right]\), then |AB| is equal to
460
2000
3000
-7000
17.
If \(\left|\begin{array}{lll}2 & 3 & 2 \\ x & x & x \\ 4 & 9 & 1\end{array}\right|+3=0\), then the value of x is
3
0
-1
1
18.
Given that \(A=\left[a_{i j}\right]\) is a square matrix of order 3 x 3 and |A| = -7, then the value of \(\sum_{i=1}^3 a_{i 2} A_{i 2}\), where \(A_{i j}\) denotes the cofactor of element \(a_{i j}\) is
7
-7
0
49
19.
Let \(A=\left[\begin{array}{ccc}1 & \sin \alpha & 1 \\ -\sin \alpha & 1 & \sin \alpha \\ -1 & -\sin \alpha & 1\end{array}\right]\), where \(0 \leq \alpha \leq 2 \pi\), then
|A| = 0
\(|A| \in(2, \infty)\)
\(|A| \in(2,4)\)
\(|A| \in[2,4]\)
20.
Given that A is a non-singular matrix of order 3 such that \(A^2=2 A\), then the value of |2A| is
4
8
64
16
21.
Value of k, for which \(A=\left[\begin{array}{cc}k & 8 \\ 4 & 2 k\end{array}\right]\) is a singular matrix, is
4
-4
± 4
0
22.
If \(\left|\begin{array}{ll}2 & 4 \\ 5 & 1\end{array}\right|=\left|\begin{array}{cc}2 x & 4 \\ 6 & x\end{array}\right|\), then the possible value(s) of x is/are
3
\(\sqrt{3}\)
\(-\sqrt{3}\)
\(\sqrt{3},-\sqrt{3}\)
23.
The value of |A|, if \(A=\left[\begin{array}{ccc}0 & 2 x-1 & \sqrt{x} \\ 1-2 x & 0 & 2 \sqrt{x} \\ -\sqrt{x} & -2 \sqrt{x} & 0\end{array}\right]\), where \(x \in R^{+}\), is
\((2 x+1)^2\)
0
\((2 x+1)^3\)
None of these
24.
If the area of the tríangle with vertices (-3,0), (3, 0) and (0, k) is 9 sq units, then the value's of k will be
9
土3
-9
6
25.
Let A be the area of a triangle having vertices \(\left(x_1, y_1\right),\left(x_2, y_2\right)\) and \(\left(x_3, y_3\right)\). Which of the following is correct?
\(\left|\begin{array}{lll}x_1 & y_1 & 1 \\ x_2 & y_2 & 1 \\ x_3 & y_3 & 1\end{array}\right|= \pm A\)
\(\left|\begin{array}{lll}x_1 & y_1 & 1 \\ x_2 & y_2 & 1 \\ x_3 & y_3 & 1\end{array}\right|= \pm 2 A\)
\(\left|\begin{array}{lll}x_1 & y_1 & 1 \\ x_2 & y_2 & 1 \\ x_3 & y_3 & 1\end{array}\right|= \pm A/2\)
\(\left|\begin{array}{lll}x_1 & y_1 & 1 \\ x_2 & y_2 & 1 \\ x_3 & y_3 & 1\end{array}\right|= \pm A^2\)
26.
If \(\left[\begin{array}{lll}1 & 2 & 1 \\ 2 & 3 & 1 \\ 3 & a & 1\end{array}\right]\) is non-singular matrix and \(a \in A\), then the set A is
R
{0}
{4}
R - {4}
27.
Let A be a skew- symmetric matrix of order 3 . If |A| = x, then (2023)x is equal to
2023
\(\frac{1}{2023}\)
\((2023)^2\)
1
28.
If \(\left|\begin{array}{lll}\alpha & 3 & 4 \\ 1 & 2 & 1 \\ 1 & 4 & 1\end{array}\right|=0\), then the value of \(\alpha\) is
1
2
3
4
29.
The value of the determinant \(\left|\begin{array}{ccc}2 & 7 & 1 \\ 1 & 1 & 1 \\ 10 & 8 & 1\end{array}\right|\) is
47
-79
49
-51
30.
If A is a square matrix of order 2 and |4| = -2, then value of |5A' | is
- 50
- 10
10
50
31.
If a, b, c are in AP, then the value of
\(\left|\begin{array}{ccc}
x+1 & x+2 & x+a \\
x+2 & x+3 & x+b \\
x+3 & x+4 & x+c
\end{array}\right| \text { is }\)
4
-3
0
abc
32.
If a, b. c are all distinct, and \(\left|\begin{array}{lll} a & a^{2} & 1+a^{3} \\ b & b^{2} & 1+b^{3} \\ c & c^{2} & a+c^{3} \end{array}\right|=0\) then the value of abc is
0
-1
3
-3
33.
Let A be a square matrix of order 3 x 3 and k a scalar, then |kA| is equal to
k|A|
|k||A|
k3|A|
none of these
34.
Let A be a non-angular square matrix of order 3 x 3, then |A . adj A| is equal to
|A|3
|A|2
|A|
3|A|
35.
If A and B are invertible matrices then which of the following is not correct
\(A d j A=|A| \cdot A^{-1}\)
\(\operatorname{det}\left(A^{-1}\right)=(\operatorname{det} A)^{-1}\)
\((A B)^{-1}=B^{-1} A^{-1}\)
\((A+B)^{-1}=A^{-1}+B^{-1}\)
36.
The adjoint of the matrix \(A=\left[\begin{array}{ll} 1 & 2 \\ 3 & 4 \end{array}\right]\) is
\(\left[\begin{array}{ll} 4 & 2 \\ 3 & 1 \end{array}\right]\)
\(\left[\begin{array}{rr} -4 & 2 \\ 3 & -1 \end{array}\right]\)
\(\left[\begin{array}{rr} 4 & -2 \\ -3 & 1 \end{array}\right]\)
\(\left[\begin{array}{rr} 1 & -2 \\ -3 & 4 \end{array}\right]\)
37.
If A and B are square matrices of same order,then
\(|A B|=|A| \cdot|B|\)
\(|A B| \neq|A| \cdot|B|\)
\(|A B|=\frac{|A|}{|B|},|B| \neq 0\)
\(|A B|=\frac{|B|}{|A|},|A| \neq 0\)
38.
Asquare matrix A is said to be non-singular, if
\(|A|=0\)
\(|A| \neq 0\)
\(|A|=-1\)
\(|A|=1\)
39.
If \(f(t)=\left[\begin{array}{ccc} \cos t & t & 1 \\ 2 \sin t & t & 2 t \\ \sin t & t & t \end{array}\right] \text { , then } \lim _{t \rightarrow 0} \frac{f(t)}{t^{2}}\) is equal to
0
-1
2
3
40.
if a, b, c are in AP, then determinant
\(\left|\begin{array}{lll}
x+2 & x+3 & x+2 a \\
x+3 & x+4 & x+2 b \\
x+4 & x+5 & x+2 c
\end{array}\right|\) is
zero
1
x
2x
41.
For what value of k, the following system of linear equations will have infinite solutions?
\( x-y+z=3 \)
\(2 x+y-z=2 \)
\(-3 x-2 k y+6 z=3\)
k ≠ 2
k = 0
k = 3
k = -1
42.
Given,2x - y + 2z = 2, x - 2y + Z = - 4 and x + y + λz= 4, then the value of Asuch that the given system of equation has no solution is
3
1
0
-3
43.
The simultaneous equations kx + 2y -z = 1, (k -1)y - 2z = 2, (k + 2)z = 3 have only one solution when
k = -2
k = -1
k = 0
k = 1
44.
For the system of equations 5x + 2y = 4; 7x +3y = 5 the values of x and yare respectively.
x = 2, y = -3
x = 2, y = 3
x = -2, y = -3
x = -2, y = 3
45.
If A is singular matrix and \((\operatorname{adj} A) B \neq O\) then
there is unique solution
solution does not exist
there are infinitely many solutions
None of the above
46.
If A is an invertible matrix of order 2, then det (A-1) is equal to
det (A)
\(\frac{1}{\operatorname{det}(A)}\)
1
zero
47.
If \(A=\left|\begin{array}{llr} 2 & \lambda & -3 \\ 0 & 2 & 5 \\ 1 & 1 & 3 \end{array}\right|\) then A-I exists, if
\(\lambda=2\)
\(\lambda \neq 2\)
\(\lambda \neq-2\)
None of these
48.
If \(A=\left[\begin{array}{cc} 2 & 3 \\ -4 & -6 \end{array}\right]\) then which of the following is true?
\(A(\operatorname{adj} A) \neq|A| I\)
\(A(\operatorname{adj} A) \neq(\operatorname{adj} A) A\)
\(A(\operatorname{adj} A)=(\operatorname{adj} A) A=|A| I=\left[\begin{array}{ll} 0 & 0 \\ 0 & 0 \end{array}\right]\)
None of the above
49.
Let A be the non-singular square matrix of order 3 x 3, then [adj A Iis equal to
|A|
IAI2
IA|3
3|A|
50.
If \(\Delta=\left|\begin{array}{lll} a_{11} & a_{12} & a_{13} \\ a_{21} & a_{22} & a_{23} \\ a_{31} & a_{32} & a_{33} \end{array}\right|\) and Aij is cofactor of aij, then value of Δ is given by
a11A31+a12+A32+a13A33
a11A11 + a12A21+ a13A31
a21A11 + a22A12 + a2A13
a11A11 + a21A21+ a31A31
51.
If Mu = - 40, M12 = - 10 and M13 = 35 of the determinant \(\Delta=\left|\begin{array}{rrr} 1 & 3 & -2 \\ 4 & -5 & 6 \\ 3 & 5 & 2 \end{array}\right|\) then the value of \(\Delta\) is
-80
60
70
100
52.
If \(\Delta=\left|\begin{array}{lll} a & h & g \\ h & b & f \\ g & f & c \end{array}\right|\) then the cofactor A21 is
-(he + fg)
fg -hc
fg + hc
hc-fg
53.
If \(\Delta=\left|\begin{array}{lll} 1 & a & b c \\ 1 & b & c a \\ 1 & c & a b \end{array}\right|\) then the minor M31 is
-c(a2 - b2)
c(b2-a2)
c(a2 + b2)
c(a2-b2)
54.
Minor of an element of a determinant of order \(n(n \geq 2)\) is a determinant of order.
n
n-1
n-2
n+1
55.
The area of the triangle formed by 3 collinear points is
one
two
zero
four
56.
If area of a triangle is 35 sq. units with vertices (2, - 6), (5, 4) and (k, 4),then k is
12
-2
-12, -2
12, -2
57.
Area of the triangle whose vertices are (a, b + c), (b, c + a) and (c, a + b), is
2 sq units
3 sq unit
0 sq unit
None of the above
58.
The area of triangle with vertices (x1 yl), (x2'y2) and (x3'y3) is
\(\Delta=\frac{1}{2}\left|\begin{array}{lll} x_{1} & y_{1} & 1 \\ x_{2} & y_{2} & 1 \\ x_{3} & y_{3} & 1 \end{array}\right|\)
\(\Delta=\frac{1}{2}\left|\begin{array}{lll} x_{1} & y_{1} & 1 \\ y_{1} & y_{2} & 1 \\ x_{3} & y_{3} & 1 \end{array}\right|\)
\(\Delta=\left|\begin{array}{lll} x_{1} & y_{1} & 1 \\ x_{2} & y_{2} & 1 \\ x_{3} & y_{3} & 1 \end{array}\right|\)
None of these
59.
The determinant \(\left|\begin{array}{rrr} x & \sin \theta & \cos \theta \\ -\sin \theta & -x & 1 \\ \cos \theta & 1 & x \end{array}\right|\) is
independent of θ only
independent of x only
independent of both ө and x
None of the above
60.
Iff \(f(x)=\left|\begin{array}{ccc} 0 & x-a & x-b \\ x+a & 0 & x-c \\ x+b & x+c & 0 \end{array}\right|\) then
f(a) = 0
f(b) = 0
f(0) = 0
f(1) = 0
61.
Let \(\Delta=\left|\begin{array}{lll} A x & x^{2} & 1 \\ B y & y^{2} & 1 \\ C z & z^{2} & 1 \end{array}\right| \text { and } \Delta_{1}=\left|\begin{array}{ccc} A & B & C \\ x & y & z \\ z y & z x & x y \end{array}\right|\) then
\(\Delta_{1}=-\Delta\)
\(\Delta \neq \Delta_{1}\)
\(\Delta^{2}-\Delta_{1}=0\)
None of these
62.
If \(\left|\begin{array}{cc} x & 2 \\ 18 & x \end{array}\right|=\left|\begin{array}{cc} 6 & 2 \\ 18 & 6 \end{array}\right|\) then, x is equal to
6
\(\pm 6\)
-6
zero
63.
Let A = \(\left[ \begin{matrix} 1 & sin\theta & 1 \\ -sin\theta & 1 & sin\theta \\ -1 & -sin\theta & 1 \end{matrix} \right] \), where 0 ≤ θ ≤2ㅠ.Then
Det (A) = 0
Det (A) ∈ (2, ∞)
Det (A) ∈ (2, 4)
Det (A) ∈ [2, 4]
64.
If A is an invertible matrix of order 2, then det (A–1) is equal to
det (A)
\(\frac{1}{det(A)}\)
1
0
65.
If Δ = \(\left| \begin{matrix} { a }_{ 11 } & { a }_{ 12 } & { a }_{ 13 } \\ { a }_{ 21 } & { a }_{ 22 } & { a }_{ 23 } \\ { a }_{ 31 } & { a }_{ 32 } & { a }_{ 33 } \end{matrix} \right| \) and Aij is Cofactors of aij, then value of Δ is given by
a11 A31+ a12 A32 + a13 A33
a11 A11+ a12 A21 + a13 A31
a21 A11+ a22 A12 + a23 A13
a11 A11+ a21 A21 + a31 A31
66.
Which of the following is correct
Determinant is a square matrix
Determinant is a number associated to a matrix
Determinant is a number associated to a square matrix
None of these
67.
If \(\begin{vmatrix} x & 2 \\ 18 & x \end{vmatrix}=\begin{vmatrix} 6 & 2 \\ 18 & 6 \end{vmatrix}\) , then x is equal to
6
土6
-6
0
68.
A and B are invertible matrices of the same order such that |(AB)-1| = 8, If |A| = 2, then |B| is
16
4
6
\(\frac{1}{16}\)
69.
Let x, yeR, then the determinant \(\triangle =\) \(\left| \begin{matrix} cosx & -sinx & 1 \\ sinx & cosx & 1 \\ cos(x+y) & -sin(x+y) & 0 \end{matrix} \right| \), lies in the interval
\([-\sqrt { 2 } ,\sqrt { 2 } ]\)
[-1, 1]
\([-\sqrt { 2 } ,1]\)
\([-1,\sqrt { 2 } ]\)
70.
Let f(x) = \(\left| \begin{matrix} cos \ x & 2 \ sin \ x & sin \ x \\ x & x & x \\ 1 & 2x & x \end{matrix} \right| \), then \(\lim _{ x\rightarrow 0 }{ \frac { f(x) }{ { x }^{ 2 } } } \) is equal to
0
-1
2
3
71.
Let A be a square matrix of order 2 × 2, then |KA| is equal to
K|A|
K²|A|
K3|A|
2K|A|
72.
Let Δ = \(\left| \begin{matrix} { Ax }^{ 2 } & x^{ 3 } & 1 \\ { By }^{ 2 } & { y }^{ 3 } & 1 \\ { Cz }^{ 2 } & { z }^{ 3 } & 1 \end{matrix} \right| \) and \({ \triangle }_{ 1 }=\left| \begin{matrix} Ax & By & Cz \\ { x }^{ 2 } & { y }^{ 2 } & { z }^{ 2 } \\ yz & zx & xy \end{matrix} \right| \), then
Δ + Δ1 = 0
Δ ≠ Δ1
Δ = xΔ1
Δ - Δ1 = 0
73.
The value \(\left| \begin{matrix} 6 & 0 & -1 \\ 2 & 1 & 4 \\ 1 & 1 & 3 \end{matrix} \right| \) is
-7
7
8
10
74.
If \(\begin{vmatrix} 2x & -1 \\ 4 & 2 \end{vmatrix}=\begin{vmatrix} 3 & 0 \\ 2 & 1 \end{vmatrix}\) then x is
3
\(\frac { 2 }{ 3 } \)
\(\frac { 3 }{ 2 } \)
\(-\frac { 1 }{ 4 } \)
75.
Assertion If A is a non-singular matrix, then A-1 exist.
Reason Determinant of a non-singular matrix is zero.
(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
76.
Assertion If |A| = 4, then |A-1| = - 4.
Reason |A-1| = \(\frac{1}{|A|}\)
(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
77.
Assertion adj(adj A) = |A|n-2. A
Reason |adj A| = |A|n-1
(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
78.
Assertion \(\begin{bmatrix}
0& -1& 2\\
1& 0& 3\\
-2& -3& 0\\
\end{bmatrix}\)= 0
Reason Determinant of odd ordered skew-symmetric is zero.
(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
79.
Assertion: The matrix A = \(\begin{bmatrix}
0& 2& 4\\
2& 0& 8\\
4& 8& 0\\
\end{bmatrix}\)is a skew symmetric matrix
Reason: For the given matrix 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.
80.
Assertion: The matrix \(\begin{bmatrix}
2& 5& 7\\
5& 4& 9\\
7& 9& 3\\
\end{bmatrix}\)is a symmetric matrix
Reason: For the given matrix 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.
81.
Assertion: The value of determinant of a matrix and the value of determinant of its transpose are equal.
Reason: The value of determinant remains unchanged if its rows and columns are interchanged.
(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.
82.
Assertion: The matrix A=\(\begin{bmatrix}
2& 3& -\frac{1}{2}\\
7& 3& 2\\
3& 1& 1\\
\end{bmatrix}\)is singular.
Reason: The value of determinant of matrix A is zero.
(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.
83.
Let A be a 2 \(\times\)2 matrix
Assertion: adj (adj A) = A
Reason: |adjA = |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.
84.
Assertion: \(\Delta\)= a11A11 + a12A12 + a13A13 where, Aij is cofactor of aij
Reason: \(\Delta\)\(\overset{aj}{=}\)Sum of the products of elements of any row (or column) with their corresponding cofactors.
(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 points A(a, b + c), B(b, c + a) and C(c,a + b) are collinear.
Reason: Area of a triangle with three collinear points is zero.
(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: \(\Delta =\begin{vmatrix}
a_{1}& a_{2}& a_{3}\\
b_{1}& b_{2}& b_{3}\\
ka_{1}& ka_{2}& ka_{3}\\
\end{vmatrix}\)=0
Reason: If corresponding elements of any two rows of a determinant are proportional, then its value is zero.
(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.
Let A = [aij] be a matrix of order 3 \(\times\)3
Assertion: Expansion of determinant of A along second row and first column gives the same value.
Reason: Expanding a determinant along any row or column gives the same value.
(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.
Consider the system
2x + 3y + 6z = 8
x + 2y + 3z = 5
x + y + 3z = 4
Assertion: The above system of equation has no solution.
Reason: detA = 0 and (adj A A)B = 0, where
\(A=\begin{bmatrix}
2& 3& 6\\
1& 2& 3\\
1& 1& 3\\
\end{bmatrix}\)and \(B=\begin{bmatrix}
8 \\
5 \\
4 \\
\end{bmatrix}\)
(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.
Assertion: \(\begin{vmatrix}
cos(\theta +\alpha)&cos(\theta +\beta) &cos(\theta +\gamma ) \\
sin(\theta +\alpha )&sin(\theta +\beta ) &sin(\theta +\gamma ) \\
sin(\beta -\gamma)&sin(\gamma-\alpha) &sin(\alpha -\beta ) \\
\end{vmatrix}\) is independent of \(\theta\)
Reason: If f(\(\theta\)) = c, then f(\(\theta\)) is independent of \(\theta\).
(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.
Consider the system
x + y + z = 1
2x + 2y + 2z = 2
4x + 4y + 4z = 3
Assertion: The above system has infinitely many solutions.
Reason: For the above system det A = 0 and (adj A) B = 0, where
\(A=\begin{bmatrix}
1& 1& 1\\
2& 2& 2\\
4& 4& 4\\
\end{bmatrix}\) and \(B=\begin{bmatrix}
1 \\
2 \\
3 \\
\end{bmatrix}\)
(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: If the matrix A = \(\begin{bmatrix} 2& 2& 1\\ 1& 3& 1\\ 1& 2& 2\\ \end{bmatrix}\), then 5 A-1 = A2 - 7A + 101
Reason: If det (A - \(\lambda\)I) = \(\sum_{r=0}^{3}C_{r}\lambda^{r}\), then
C0I + C1A + C2A2 + C3A3 = 0
(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: If a, b, c are even natural numbers, then \(\Delta\)= \(\begin{bmatrix}
a-1& a& a+1\\
b-1& b& b+1\\
c-1& c& c+1\\
\end{bmatrix}\) is an even natural number.
Reason: Sum and product of two even natural number is also an even natural number.
(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.
Let A = \(\begin{bmatrix}
1& 0& a\\
2& 3& b\\
-3& 1& c\\
\end{bmatrix}\), B=\(\begin{bmatrix}
1& 0& x\\
2& 3& y\\
-3& 1& z\\
\end{bmatrix}\)and C=\(\begin{bmatrix}
1& 0& a+x\\
2& 3& b+y\\
-3& 1& c+z\\
\end{bmatrix}\)
Assertion: det A + det B = det C.
Reason: A + B = C.
(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.
94.
Consider the system of equations
x - 2y + 3z = -1
-x + y - 2z = k
x - 3y + 4z = 1
Assertion: The system of equations has no solution for k \(\neq\)3.
Reason: The determinant \(\begin{vmatrix}
{1} & {3} & {-1}\\
{-1} & {-2} & {k} \\
{1} & {4} & {1}\\
\end{vmatrix}\)\(\neq\)0, for k \(\neq\)3.
(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.
95.
Assertion: If three lines L1 : a1x + b1y+c1 = 0, L2:a2x + b2y + c2 = 0 and L3:a3x + b3y + c3 = 0 are concurrent lines, then \(\begin{vmatrix}
a_{1} & b_{1} & c_{1}\\
a_{2} & b_{2} & c_{2} \\
a_{3} & b_{3} & c_{3}\\
\end{vmatrix}\)=0
Reason: If \(\begin{vmatrix}
a_{1} & b_{1} & c_{1}\\
a_{2} & b_{2} & c_{2} \\
a_{3} & b_{3} & c_{3}\\
\end{vmatrix}\)= 0, then the lines L1, L2, L3 must be concurrent.
(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.
(c)
\(a^6\)
2.
(c)
100
3.
(d)
\(B^{-1}=\frac{1}{6} A\)
4.
(b)
\(\left[\begin{array}{cc}4 & -2 \\ 2 & 6\end{array}\right]\)
5.
(c)
\(\left[\begin{array}{cc}7 & 11 \\ -5 & 2\end{array}\right]\)
6.
(d)
16
7.
(d)
\((A+B)^{-1}=B^{-1}+A^{-1}\)
8.
(d)
28
9.
(c)
l - A
10.
(b)
2
11.
(d)
8 or -8
12.
(a)
12
13.
(d)
4
14.
(d)
\(R-\{-10\}\)
15.
(d)
\(2 \sqrt{2}\)
16.
(d)
-7000
17.
(c)
-1
18.
(b)
-7
19.
(d)
\(|A| \in[2,4]\)
20.
(c)
64
21.
(c)
± 4
22.
(d)
\(\sqrt{3},-\sqrt{3}\)
23.
(b)
0
24.
(b)
土3
25.
(b)
\(\left|\begin{array}{lll}x_1 & y_1 & 1 \\ x_2 & y_2 & 1 \\ x_3 & y_3 & 1\end{array}\right|= \pm 2 A\)
26.
(d)
R - {4}
27.
(d)
1
28.
(d)
4
29.
(a)
47
30.
(a)
- 50
31.
(c)
0
32.
(b)
-1
33.
(c)
k3|A|
34.
(a)
|A|3
35.
(d)
\((A+B)^{-1}=A^{-1}+B^{-1}\)
36.
(c)
\(\left[\begin{array}{rr} 4 & -2 \\ -3 & 1 \end{array}\right]\)
37.
(a)
\(|A B|=|A| \cdot|B|\)
38.
(b)
\(|A| \neq 0\)
39.
(a)
0
40.
(a)
zero
41.
The given system will have infinite solution, if
\(\begin{aligned} \Rightarrow &\begin{array}{l} \left|\begin{array}{ccc} 1 & -1 & 1 \\ 2 & 1 & -1 \\ -3 & -2 k & 6 \end{array}\right|=0 \\ 6 k-18=0 \Rightarrow k=3 \end{array} \end{aligned}\)
Note There is no need to verify (adj A) B = O. For k = 3.
42.
The given system of equations will have no solution, if \(|A|=0\)
\(\Rightarrow \left|\begin{array}{ccc} 2 & -1 & 2 \\ 1 & -2 & 1 \\ 1 & 1 & \lambda \end{array}\right|=0\)
\(\Rightarrow 2(-2 \lambda-1)+(\lambda-1)+2(1+2)=0\)
\(\Rightarrow-3 \lambda+3=0 \Rightarrow \lambda=1 \)
43.
Given system of equations has unique solution
\(\text { if }\left|\begin{array}{ccc} k & 2 & -1 \\ 0 & k-1 & -2 \\ 0 & 0 & k+2 \end{array}\right| \neq 0\)
\(\Rightarrow k \neq-2,0,1\)
\(\therefore\)k = - 1 is the required value.
44.
From the option, we can see only option (a) satisfy both the equations
45.
If lAI = 0 and (adj A) B ≠ - 0, then system of equations has no solution.
46.
We know,\(A A^{-1}=I\)
\(\therefore \left|A A^{-1}\right|=|| I \mid \)
\(\Rightarrow |A|\left|A^{-1}\right|=1\)
\(\Rightarrow \left|A^{-1}\right|=\frac{1}{|A|} \)
47.
\(A^{-1} \text {exist iff }|A| \neq 0\)
48.
(c)
\(A(\operatorname{adj} A)=(\operatorname{adj} A) A=|A| I=\left[\begin{array}{ll} 0 & 0 \\ 0 & 0 \end{array}\right]\)
49.
We know, if A is non-singular matrix of order n, then
| adj(A)| = lA|n-1
50.
△ Sum of product of elements of any row (or colunm) with their corresponding cofactors
51.
\( \Delta=a_{11} A_{11}+a_{12} A_{12}+a_{13} A_{13} \\ =a_{11} M_{11}-a_{12} M_{12}+a_{13} M_{13} \\ =1 (-40)-3(-10)+(-2)(35) \\ =-40+30-70=-80 \)
52.
\(A_{21}=(-1)^{2+1} M_{21}=-M_{21}=-\left|\begin{array}{ll} h & g \\ f & c \end{array}\right|\)
53.
(d)
c(a2-b2)
54.
By defmation of minor
55.
By definition of collinearity.
56.
\(\frac{1}{2}\left|\begin{array}{ccc} 2 & -6 & 1 \\ 5 & 4 & 1 \\ k & 4 & 1 \end{array}\right|=\pm 35\)
57.
Area of triangle, \(\Delta=\frac{1}{2}\left|\begin{array}{lll} a & b+c & 1 \\ b & c+a & 1 \\ c & a+b & 1 \end{array}\right|\)
58.
By formula of area of triangle
59.
\(\text { Let } \Delta=\left|\begin{array}{rrr} x & \sin \theta & \cos \theta \\ -\sin \theta & -x & 1 \\ \cos \theta & 1 & x \end{array}\right| \)
\( =x\left(-x^{2}-1\right)-\sin \theta(-x \sin \theta-\cos \theta) +\cos \theta(-\sin \theta+x \cos \theta)\)
\( =-x^{3}-x+x \sin ^{2} \theta+\sin \theta \cos \theta-\sin \theta \cos \theta+x \cos ^{2} \theta \\ =-x^{3}-x+x\left(\sin ^{2} \theta+\cos ^{2} \theta\right)=-x^{3}-x+x \\ \left[\because \sin ^{2} \theta+\cos ^{2} \theta=1\right] \)
60.
Clearly,
\( f(a) =\left|\begin{array}{ccc} 0 & 0 & a-b \\ 2 a & 0 & a-c \\ a+b & a+c & 0 \end{array}\right| \)
\(=[(a-b)\{2 a \cdot(a+c)\}] \neq 0 \)
\( \therefore \ f(b) =\left|\begin{array}{ccc} 0 & b-a & 0 \\ b+a & 0 & b-c \\ 2 b & b+c & 0 \end{array}\right|\)
\( =-(b-a)[2 b(b-c)] \)
\( =-2 b(b-a)(b-c) \neq 0 \)
61.
\( \Delta_{1} =\left|\begin{array}{ccc} A & B & C \\ x & y & z \\ z y & z x & x y \end{array}\right| =\left|\begin{array}{ccc} A & x & z y \\ B & y & z x \\ C & z & x y \end{array}\right| \\ =\frac{1}{x y z}\left|\begin{array}{lll} A x & x^{2} & x y z \\ B y & y^{2} & x y z \\ C z & z^{2} & x y z \end{array}\right|=\frac{x y z}{x y z}\left|\begin{array}{ccc} A x & x^{2} & 1 \\ B y & y^{2} & 1 \\ C z & z^{2} & 1 \end{array}\right|=\Delta \)
62.
Given \(\left|\begin{array}{cc} x & 2 \\ 18 & x \end{array}\right|=\left|\begin{array}{cc} 6 & 2 \\ 18 & 6 \end{array}\right| \Rightarrow x^{2}-36=36-36\)
\(\Rightarrow \quad x^{2}=36 \Rightarrow x=\pm 6\)
63.
(d)
Det (A) ∈ [2, 4]
64.
(b)
\(\frac{1}{det(A)}\)
65.
(d)
a11 A11+ a21 A21 + a31 A31
66.
(c)
Determinant is a number associated to a square matrix
67.
(b)
土6
68.
As \(\left| { (AB) }^{ -1 } \right| =\frac { 1 }{ |AB| } =\frac { 1 }{ |A||B| } \)
\(\Rightarrow 8=\frac { 1 }{ 2|B| } \Rightarrow B=\frac { 1 }{ 16 } \)
69.
Performing \({ R }_{ 3 }\rightarrow { R }_{ 3 }-{ cosyR }_{ 1 }+{ siny }{ R }_{ 2 }\)
we get on simplification
\(\triangle =sin \ y-cos \ y=\sqrt { 2 } .sin\left( y-\frac { \pi }{ 4 } \right) \le \sqrt { 2 } \)
As -1 \(\le sin\left( y-\frac { \pi }{ 4 } \right) \le 1\)
⇒ \(-\sqrt { 2 } \le \sqrt { 2 } \) \(sin\left( y-\frac { \pi }{ 4 } \right) \le \sqrt { 2 } \)
∴ \([-\sqrt { 2 } ,\sqrt { 2 } ]\)
70.
As C2⟶ C2 - 2C3 gives
\(\left| \begin{matrix} cos\ x & 2sinx & sinx \\ x & x & x \\ 1 & 2x & x \end{matrix} \right| \) = -x(x cos x - sin x)
= -x2 cos x + x sin x
\(\lim _{ x\rightarrow 0 }{ \frac { f(x) }{ { x } } } \) = \(\lim _{ x\rightarrow 0 }{ \left( \frac { -{ x }^{ 2 }cos \ x+x \ sin \ x }{ { x }^{ 2 } } \right) } \)
= \(\lim _{ x\rightarrow 0 }{ (-cosx) } +\lim _{ x\rightarrow 0 }{ \left( \frac { sinx }{ x } \right) } \)
= - 1 + 1 = 0
71.
As if A = \(\begin{bmatrix} a & b \\ c & d \end{bmatrix}\) then \(\left| A \right| =\begin{bmatrix} a & b \\ c & d \end{bmatrix}\)
\(KA=\begin{bmatrix} Ka & Kb \\ Kc & Kd \end{bmatrix}\) and \(\left| KA \right| =\begin{bmatrix} Ka & Kb \\ Kc & Kd \end{bmatrix}\)
\(={ K }^{ 2 }\begin{vmatrix} a & b \\ c & d \end{vmatrix}={ K }^{ 2 }|A|\)
72.
\({ \triangle }_{ 1 }=\left| \begin{matrix} Ax & By & Cz \\ { x }^{ 2 } & { y }^{ 2 } & { z }^{ 2 } \\ yz & zx & xy \end{matrix} \right| \)
C1 ⟶ xC1, C2 ⟶ yC2 and C3 ⟶ zC3 and dividing determinat by xyz
= \(\frac { 1 }{ xyz } \left| \begin{matrix} { Ax }^{ 2 } & { By }^{ 2 } & { Cz }^{ 2 } \\ { x }^{ 2 } & { y }^{ 2 } & { z }^{ 2 } \\ xyz & xyz & xyz \end{matrix} \right| \)
Taking xyz common from R3, we get
\(\frac { xyz }{ xyz } \left| \begin{matrix} { Ax }^{ 2 } & { By }^{ 2 } & { Cz }^{ 2 } \\ { x }^{ 2 } & { y }^{ 2 } & { z }^{ 2 } \\ 1 & 1 & 1 \end{matrix} \right| \)
= \(\left| \begin{matrix} { Ax }^{ 2 } & { By }^{ 2 } & { Cz }^{ 2 } \\ { x }^{ 2 } & { y }^{ 2 } & { z }^{ 2 } \\ 1 & 1 & 1 \end{matrix} \right| =\left| \begin{matrix} { Ax }^{ 2 } & x^{ 3 } & 1 \\ { By }^{ 2 } & { y }^{ 3 } & 1 \\ { Cz }^{ 2 } & { z }^{ 3 } & 1 \end{matrix} \right| \)=Δ
⇒ Δ1 - Δ = 0
73.
Δ = 6(-1)- 1(1) = -7
74.
As \(\begin{vmatrix} 2x & -1 \\ 4 & 2 \end{vmatrix}=\begin{vmatrix} 3 & 0 \\ 2 & 1 \end{vmatrix}\)
⇒ 4x + 4 = 3 - 0
⇒ x = \(-\frac { 1 }{ 4 } \)
75.
(c) A is correct; R is incorrect
76.
(d) R is correct; A is incorrect
77.
(a) Both A and R are correct; R is the correct explanation of A
78.
(a) Both A and R are correct; R is the correct explanation of A
79.
(d) Assertion is incorrect, reason is correct.
80.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
81.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
82.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
83.
(b) Assertion is correct, reason is correct; reason is not a correct explanation for assertion
84.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
85.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
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.
(c) Assertion is correct, reason is incorrect
89.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
90.
(d) Assertion is incorrect, reason is correct.
91.
(d) Assertion is incorrect, reason is correct.
92.
(d) Assertion is incorrect, reason is correct.
93.
(c) Assertion is correct, reason is incorrect
94.
(a) Assertion is correct, reason is correct; reason is a correct explanation for assertion.
95.
(c) Assertion is correct, reason is incorrect
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