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Byju's Answer
Standard XII
Mathematics
Adjoint of a Matrix
text If A= be...
Question
If
A
=
[
3
−
1
4
−
1
]
and
A
10
=
[
a
11
a
12
a
21
a
22
]
,
then
a
11
+
a
22
=
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Solution
A
=
[
3
−
1
4
−
1
]
=
[
1
0
0
1
]
+
[
2
−
1
4
−
2
]
=
I
+
B
B
2
=
[
2
−
1
4
−
2
]
[
2
−
1
4
−
2
]
=
[
0
0
0
0
]
Now,
A
10
=
(
I
+
B
)
10
=
I
+
10
C
1
B
+
10
C
2
B
2
+
10
C
3
B
3
+
.
.
.
+
10
C
10
B
10
=
I
+
10
B
=
[
1
0
0
1
]
+
10
[
2
−
1
4
−
2
]
=
[
21
−
10
40
−
19
]
∴
a
11
+
a
22
=
21
−
19
=
2
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0
Similar questions
Q.
If
A
=
[
3
−
1
4
−
1
]
and
A
10
=
[
a
11
a
12
a
21
a
22
]
,
then
a
11
+
a
22
=
Q.
Let M be a
3
×
3
matrix satisying
M
⎡
⎢
⎣
0
1
0
⎤
⎥
⎦
=
⎡
⎢
⎣
−
1
2
3
⎤
⎥
⎦
,
M
⎡
⎢
⎣
1
−
1
0
⎤
⎥
⎦
=
⎡
⎢
⎣
1
1
−
1
⎤
⎥
⎦
,
a
n
d
M
⎡
⎢
⎣
1
1
1
⎤
⎥
⎦
=
⎡
⎢
⎣
0
0
12
⎤
⎥
⎦
.
Then, find the sum of the diagonal entries of M.
Q.
If
A
=
⎡
⎢
⎣
a
2
−
1
−
1
1
2
2
−
1
1
⎤
⎥
⎦
,
where
(
a
≠
11
3
)
and
d
e
t
.
(
adj(adj
A
)
)
=
(
23
)
4
,
then the value of
a
is
Q.
Find a and b if
a
[
1
7
]
−
[
3
b
]
=
[
2
24
]
Q.
What is the inverse of the matrix
[
−
3
2
5
−
1
]
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