MCQ
The order of $\begin{bmatrix}\text{x}&\text{amp;}\text{ y}&\text{amp; }\text{z}\end{bmatrix}$ $\begin{bmatrix}\text{x} &\text{amp;}\text{ h}&\text{amp;}\text{ g} \\\text{h} &\text{amp;}\text{ b}&\text{amp; }\text{f}\\\text{g} &\text{amp;}\text{ f}&\text{amp; }\text{c} \end{bmatrix}\begin{bmatrix}\text{x}\\\text{y}\\\text{z}\end{bmatrix}$ is:
  • A
    $3\times1$
  • $1\times1$
  • C
    $1\times3$
  • D
    $3\times3$

Answer

Correct option: B.
$1\times1$
Let $\text{ABC}=\begin{bmatrix}\text{x}&\text{amp;}\text{ y}&\text{amp; }\text{z}\end{bmatrix}\begin{bmatrix}\text{x} &\text{amp;}\text{ h}&\text{amp;}\text{ g} \\\text{h} &\text{amp;}\text{ b}&\text{amp; }\text{f}\\\text{g} &\text{amp;}\text{ f}&\text{amp; }\text{c} \end{bmatrix}\begin{bmatrix}\text{x}\\\text{y}\\\text{z}\end{bmatrix}$

Here, the order of $\text{A}$ is $1\times3$

Order of $\text{B}$ is $3\times3$

Since, matrix multiplication satisfies associative property

$\text{i}.\text{e}. (\text{AB})\text{C} = \text{A}(\text{BC})$


Hence, the order of $\text{AB}$ is $1\times3$

Hence, the order of $\text{ABC}$ is $1\times1$

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