MCQ
If $A = \left[ {\begin{array}{*{20}{c}}4&2\\{ - 1}&1\end{array}} \right]$and $I$ is the identity matrix of order $2$, then $(A - 2I)(A - 3I) = $
  • A
    $I$
  • $O$
  • C
    $\left[ {\begin{array}{*{20}{c}}1&0\\0&0\end{array}} \right]$
  • D
    $\left[ {\begin{array}{*{20}{c}}0&0\\0&1\end{array}} \right]$

Answer

Correct option: B.
$O$
b
(b) $(A - 2I)\,(A - 3I) = \left[ {\begin{array}{*{20}{c}}2&2\\{ - 1}&{ - 1}\end{array}} \right]\,\left[ {\begin{array}{*{20}{c}}1&2\\{ - 1}&{ - 2}\end{array}} \right]\, = \,\left[ {\begin{array}{*{20}{c}}0&0\\0&0\end{array}} \right] = O$.

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