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Mathematics
Mathematics
Problem
Consider the matrix
A
=
(
1
k
2
0
1
−
1
3
4
k
)
A=\begin{pmatrix}1 & k & 2\\ 0 & 1 & -1\\ 3 & 4 & k\end{pmatrix}
A
=
1
0
3
k
1
4
2
−
1
k
, where
k
>
0
k>0
k
>
0
. If
(
adj
A
)
12
=
4
(\text{adj}\,A)_{12}=4
(
adj
A
)
12
=
4
, then
k
k
k
equals a)
−
2
-2
−
2
b)
4
4
4
c)
2
2
2
d)
2
3
2\sqrt{3}
2
3
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