MCQ
If $X = \left[ {\begin{array}{*{20}{c}}3&{ - 4}\\1&{ - 1}\end{array}} \right]$, then the value of ${X^n}$ is
  • A
    $\left[ {\begin{array}{*{20}{c}}{3n}&{ - 4n}\\n&{ - n}\end{array}} \right]$
  • B
    $\left[ {\begin{array}{*{20}{c}}{2 + n}&{5 - n}\\n&{ - n}\end{array}} \right]$
  • C
    $\left[ {\begin{array}{*{20}{c}}{{3^n}}&{{{( - 4)}^n}}\\{{1^n}}&{{{( - 1)}^n}}\end{array}} \right]$
  • None of these

Answer

Correct option: D.
None of these
d
(d) $X = \left[ {\begin{array}{*{20}{c}}3&{ - 4}\\1&{ - 1}\end{array}} \right] \Rightarrow {X^2} = \left[ {\begin{array}{*{20}{c}}5&{ - 8}\\2&{ - 3}\end{array}} \right]$.

Clearly for $n = 2$, the matrices in $(a), (b), (c)$ do not tally with $\left[ {\begin{array}{*{20}{c}}5&{ - 8}\\2&{ - 3}\end{array}} \right]$.

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