3 and 4 .Determinants and Matrices
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यदि $A=\left[\begin{array}{cc}1 & 0 \\ 0 & -1\end{array}\right]$ तथा $B=\left[\begin{array}{cc}0 & 1 \\ 1 & 0\end{array}\right]$ है तो $A B=\left[\begin{array}{cc}0 & 1 \\ -1 & 0\end{array}\right]$ और $\quad BA =\left[\begin{array}{cc}0 & -1 \\ 1 & 0\end{array}\right]$ है। स्पष्टतया $AB \neq BA$ है।
अत: आव्यूह गुणन क्रम-विनिमेय नहीं होता है।

Option A
Option B
Option C
Option D

Solution

This does not mean that $\mathrm{AB} \neq \mathrm{BA}$ for every pair of matrices $\mathrm{A}, \mathrm{B}$ for which $\mathrm{AB}$ and $\mathrm{BA}$, are defined. For instance,

If $A=\left[\begin{array}{ll}1 & 0 \\ 0 & 2\end{array}\right], B=\left[\begin{array}{ll}3 & 0 \\ 0 & 4\end{array}\right],$ then $A B=B A=\left[\begin{array}{ll}3 & 0 \\ 0 & 8\end{array}\right]$

Observe that multiplication of diagonal matrices of same order will be commutative.

Standard 12
Mathematics

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