

NCERT Solutions Class 12 Maths Chapter 4 PDF Download Link
CBSE Class 12th Toppers List 2024
Solve The Following Questions NCERT Solutions for Class 12 Maths Chapter 4 Exercise 4.4 Determinants
Question 1. Write minors and cofactors of the elements of the following determinants: (i)
(ii)
Solution :
(i) Let
Minor of element
a
ij
is M
ij.
∴M
11
= minor of element
a
11
= 3
M
12
= minor of element
a
12
= 0
M
21
= minor of element
a
21
= −4
M
22
= minor of element
a
22
= 2
Cofactor of
a
ij
is A
ij
= (−1)
i + j
M
ij
.
∴A
11
= (−1)
1+1
M
11
= (−1)
2
(3) = 3
A
12
= (−1)
1+2
M
12
= (−1)
3
(0) = 0
A
21
= (−1)
2+1
M
21
= (−1)
3
(−4) = 4
A
22
= (−1)
2+2
M
22
= (−1)
4
(2) = 2
(ii) Let
Minor of element
a
ij
is M
ij
.
∴M
11
= minor of element
a
11
=
d
M
12
= minor of element
a
12
=
b
M
21
= minor of element
a
21
=
c
M
22
= minor of element
a
22
=
a
Cofactor of
a
ij
is A
ij
= (−1)
i + j
M
ij.
∴A
11
= (−1)
1+1
M
11
= (−1)
2
(
d
) =
d
A 12 = (−1) 1+2 M 12 = (−1) 3 ( b ) = − b
A 21 = (−1) 2+1 M 21 = (−1) 3 ( c ) = − c A 22 = (−1) 2+2 M 22 = (−1) 4 ( a ) = a
Solution :
A
11
= cofactor of
a
11
= (−1)
1+1
M
11
= 1
A
12
= cofactor of
a
12
= (−1)
1+2
M
12
= 0
A
13
= cofactor of
a
13
= (−1)
1+3
M
13
= 0
A
21
= cofactor of
a
21
= (−1)
2+1
M
21
= 0
A
22
= cofactor of
a
22
= (−1)
2+2
M
22
= 1
A
23
= cofactor of
a
23
= (−1)
2+3
M
23
= 0
A
31
= cofactor of
a
31
= (−1)
3+1
M
31
= 0
A
32
= cofactor of
a
32
= (−1)
3+2
M
32
= 0
A
33
= cofactor of
a
33
= (−1)
3+3
M
33
= 1
A
11
= cofactor of
a
11
= (−1)
1+1
M
11
= 11
A
12
= cofactor of
a
12
= (−1)
1+2
M
12
= −6
A
13
= cofactor of
a
13
= (−1)
1+3
M
13
= 3
A
21
= cofactor of
a
21
= (−1)
2+1
M
21
= 4
A
22
= cofactor of
a
22
= (−1)
2+2
M
22
= 2
A
23
= cofactor of
a
23
= (−1)
2+3
M
23
= −1
A
31
= cofactor of
a
31
= (−1)
3+1
M
31
= −20
A
32
= cofactor of
a
32
= (−1)
3+2
M
32
= 13
A
33
= cofactor of
a
33
= (−1)
3+3
M
33
= 5
Solution :
We know that Δ is equal to the sum of the product of the elements of the second row with their corresponding cofactors.
∴Δ =
a
21
A
21
+
a
22
A
22
+
a
23
A
23
= 2(7) + 0(7) + 1(−7) = 14 − 7 = 7
Solution :
| NCERT Solutions for Class 12 Maths Chapter 2 Exercise 2.1 | NCERT Solutions for Class 12 Maths Chapter 2 Exercise 2.2 |
| NCERT Solutions for Class 12 Maths Chapter 2 Miscellaneous Exercise | |
and A
ij
is Cofactors of
a
ij
, then value of Δ is given by
Solution :
We know that:
Δ = Sum of the product of the elements of a column (or a row) with their corresponding cofactors
∴Δ =
a
11
A
11
+
a
21
A
21
+
a
31
A
31
Hence, the value of Δ is given by the expression given in alternative
D
.
Option (D) is correct.
