MCQ
If $A = \left( {\begin{array}{*{20}{c}}i&1\\0&i\end{array}} \right)$, then ${A^4}$ equals
  • $\left( {\begin{array}{*{20}{c}}1&{ - 4i}\\0&1\end{array}} \right)$
  • B
    $\left( {\begin{array}{*{20}{c}}{ - 1}&{ - 4i}\\0&{ - 1}\end{array}} \right)$
  • C
    $\left( {\begin{array}{*{20}{c}}{ - i}&4\\0&i\end{array}} \right)$
  • D
    $\left( {\begin{array}{*{20}{c}}1&4\\0&1\end{array}} \right)$

Answer

Correct option: A.
$\left( {\begin{array}{*{20}{c}}1&{ - 4i}\\0&1\end{array}} \right)$
a
(a) $A.A = \left[ {\begin{array}{*{20}{c}}{ - 1}&{2i}\\0&{ - 1}\end{array}} \right]$ , 

${A^4} = \left[ {\begin{array}{*{20}{c}}1&{ - 4i}\\0&1\end{array}} \right]$.

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