MCQ
If $A = \left[ {\begin{array}{*{20}{c}}2&2\\{ - 3}&2\end{array}} \right]$ and $B = \left[ {\begin{array}{*{20}{c}}0&{ - 1}\\1&0\end{array}} \right],$ then ${({B^{ - 1}}{A^{ - 1}})^{ - 1}}$=
  • $\left[ {\begin{array}{*{20}{c}}2&{ - 2}\\2&3\end{array}} \right]$
  • B
    $\left[ {\begin{array}{*{20}{c}}3&{ - 2}\\2&2\end{array}} \right]$
  • C
    $\frac{1}{{10}}\left[ {\begin{array}{*{20}{c}}2&2\\{ - 2}&3\end{array}} \right]$
  • D
    $\frac{1}{{10}}\left[ {\begin{array}{*{20}{c}}3&2\\{ - 2}&2\end{array}} \right]$

Answer

Correct option: A.
$\left[ {\begin{array}{*{20}{c}}2&{ - 2}\\2&3\end{array}} \right]$
a
(a) ${({B^{ - 1}}{A^{ - 1}})^{ - 1}} = {({A^{ - 1}})^{ - 1}}{({B^{ - 1}})^{ - 1}} = AB$

                                                                                                   (Reversal law of inverses)

$ = \,\left[ {\,\begin{array}{*{20}{c}}2&2\\{ - 3}&2\end{array}\,} \right]\,\left[ {\,\begin{array}{*{20}{c}}0&{ - 1}\\1&0\end{array}\,} \right] = \left[ {\,\begin{array}{*{20}{c}}2&{ - 2}\\2&3\end{array}\,} \right]$.

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