3 and 4 .Determinants and Matrices
easy

यदि $A$=$\left[ {\begin{array}{*{20}{c}}2&0&0\\0&2&0\\0&0&2\end{array}} \right]$ और $B = \left[ {\begin{array}{*{20}{c}}1&2&3\\0&1&3\\0&0&2\end{array}} \right],$ तो $|AB|$=

A

$4$

B

$8$

C

$16$

D

$32$

Solution

$A = \left[ {\begin{array}{*{20}{c}}2&0&0\\0&2&0\\0&0&2\end{array}} \right] = 2I$

$\therefore $ $AB = 2IB = 2B = \left[ {\begin{array}{*{20}{c}}2&4&6\\0&2&6\\0&0&4\end{array}} \right]$

 इसलिए $|AB| = \left| {\,\begin{array}{*{20}{c}}2&4&6\\0&2&6\\0&0&4\end{array}\,} \right| = 2(8) = 16$.

वैकल्पिक : $|A| = 2 \times 2 \times 2 = 8$, $|B| = 1 \times 1 \times 2 = 2$

                   $\therefore $ $|AB| = \,|A|\,|B| = 2 \times 8 = 16$.

Standard 12
Mathematics

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