MCQ
If for $AX = B,$ $B = \left[ \begin{array}{l}9\\52\\0\end{array} \right]$ and ${A^{ - 1}} = \left[ {\begin{array}{*{20}{c}}3&{ - \frac{1}{2}}&{ - \frac{1}{2}}\\{ - 4}&{\,\,\,\frac{3}{4}}&{\,\,\,\,\frac{5}{4}}\\2&{ - \frac{1}{4}}&{ - \frac{3}{4}}\end{array}} \right]$, then $X$ is equal to
  • $\left[ \begin{array}{l}1\\3\\5\end{array} \right]$
  • B
    $\left[ \begin{array}{l} - \frac{1}{2}\\ - \frac{1}{2}\\\,\,\,2\end{array} \right]$
  • C
    $\left[ \begin{array}{l} - 4\\\,\,2\\\,\,3\end{array} \right]$
  • D
    $\left[ \begin{array}{l}\,\,\,\,3\\\begin{array}{*{20}{c}}{\,\,\,\frac{3}{4}}\\{ - \,\frac{3}{4}}\end{array}\end{array} \right]$

Answer

Correct option: A.
$\left[ \begin{array}{l}1\\3\\5\end{array} \right]$
a
(a) $AX = B \Rightarrow {A^{ - 1}}.AX = {A^{ - 1}}B \Rightarrow X = {A^{ - 1}}B = \left[ \begin{array}{l}1\\3\\5\end{array} \right]$.

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