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Mathematics
Problem
Let
A
=
(
4
3
2
1
)
A=\begin{pmatrix}4 & 3\\2 & 1\end{pmatrix}
A
=
(
4
2
3
1
)
. Which of the following is
A
−
1
A^{-1}
A
−
1
? a)
(
−
1
2
3
2
1
−
2
)
\begin{pmatrix}-\dfrac12 & \dfrac32\\1 & -2\end{pmatrix}
(
−
2
1
1
2
3
−
2
)
b)
(
1
2
−
3
2
−
1
2
)
\begin{pmatrix}\dfrac12 & -\dfrac32\\-1 & 2\end{pmatrix}
(
2
1
−
1
−
2
3
2
)
c)
(
−
1
2
−
3
2
−
1
−
2
)
\begin{pmatrix}-\dfrac12 & -\dfrac32\\-1 & -2\end{pmatrix}
(
−
2
1
−
1
−
2
3
−
2
)
d)
(
−
2
3
2
1
−
1
2
)
\begin{pmatrix}-2 & \dfrac32\\1 & -\dfrac12\end{pmatrix}
−
2
1
2
3
−
2
1
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