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The inverse of matrix N begin vmatrix 2 amp 3 1... - JAMB Mathematics 2011 Question

The inverse of matrix N = \(\begin{vmatrix} 2 & 3 \\ 1 & 4\end{vmatrix}\) is
A
\(\frac{1}{5}\) \(\begin{vmatrix} 2 & 1 \ 3 & 4\end{vmatrix}\)
B
\(\frac{1}{5}\) \(\begin{vmatrix} 4 & -3 \ -1 & 2\end{vmatrix}\)
C
\(\frac{1}{5}\) \(\begin{vmatrix} 2 & -1 \ -3 & 4\end{vmatrix}\)
D
\(\frac{1}{5}\) \(\begin{vmatrix} 4 & 3 \ 1 & 2\end{vmatrix}\)
correct option: b
N = [2 3]

N-1 = \(\frac{adj N}{|N|}\)

adj N = \(\begin{vmatrix} 4 & -3 \ -1 & 2 \end{vmatrix}\)

|N| = (2 x4) - (1 x 3)

= 8 - 3

=5

N-1 = \(\frac {1}{5}\) \(\begin{vmatrix} 4 & -3 \ -1 & 2 \end{vmatrix}\)
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