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Matrices — Maths STD 12 Science — Question

Gujarat BoardEnglish MediumSTD 12 ScienceMathsMatrices1 Mark
MCQ
If $A=\left[\begin{array}{cc}2 & -3 \\ -1 & 2\end{array}\right]$ and $B=\left[\begin{array}{ll}2 & 3 \\ 1 & 2\end{array}\right]$ two matrix, then find AB ?
  • ✓
    $\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]$
  • B
    $\left[\begin{array}{ll}0 & 1 \\ 0 & 0\end{array}\right]$
  • C
    $\left[\begin{array}{ll}1 & 1 \\ 1 & 1\end{array}\right]$
  • D
    $\left[\begin{array}{ll}1 & 1 \\ 0 & 0\end{array}\right]$
✓

Answer

Correct option: A.
$\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]$
(A)
$AB =\left[\begin{array}{cc}2 & -3 \\ -1 & 2\end{array}\right]\left[\begin{array}{ll}2 & 3 \\ 1 & 2\end{array}\right]=\left[\begin{array}{cc}4-3 & 6-6 \\ -2+2 & -3+4\end{array}\right]$ $=\left[\begin{array}{ll}1 & 0 \\ 0 & 1\end{array}\right]$

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