[ * 20 c 7&1&2 9&2&1 ] , [ l 3 4 5 ] + 2 [ l 4 2 ] is equal to - Vidyadip

MCQ

$\left[ {\begin{array}{*{20}{c}}7&1&2\\9&2&1\end{array}} \right]\,\left[ \begin{array}{l}3\\4\\5\end{array} \right] + 2\left[ \begin{array}{l}4\\2\end{array} \right]$ is equal to

✓
$\left[ \begin{array}{l}43\\44\end{array} \right]$
B
$\left[ \begin{array}{l}43\\45\end{array} \right]$
C
$\left[ \begin{array}{l}45\\44\end{array} \right]$
D
$\left[ \begin{array}{l}44\\45\end{array} \right]$

✓

Answer

Correct option: A.

$\left[ \begin{array}{l}43\\44\end{array} \right]$

$\left[ {\begin{array}{*{20}{c}}7&1&2\\9&2&1\end{array}} \right]\left[ {\begin{array}{*{20}{c}}3\\4\\5\end{array}} \right] = \left[ {\begin{array}{*{20}{c}}{35}\\{40}\end{array}} \right];$
$\therefore \left[ {\begin{array}{*{20}{c}}{35}\\{40}\end{array}} \right] + \left[ {\begin{array}{*{20}{c}}8\\4\end{array}} \right] $
$= \left[ {\begin{array}{*{20}{c}}{43}\\{44}\end{array}} \right]$.

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