3 and 4 .Determinants and Matrices
easy

आव्यूह गुणन के सापेक्ष में समूह $M = \left\{ {\left. {\left( {\begin{array}{*{20}{c}}x&x\\x&x\end{array}} \right){\rm{ }}} \right|x \in R;\,x \ne 0\,} \right\}$ का तत्समक अवयव है

A

$\left( {\begin{array}{*{20}{c}}1&1\\1&1\end{array}} \right)$

B

$\frac{1}{2}\left( {\begin{array}{*{20}{c}}1&1\\1&1\end{array}} \right)$

C

$\left( {\begin{array}{*{20}{c}}1&0\\0&1\end{array}} \right)$

D

$\left( {\begin{array}{*{20}{c}}0&1\\1&0\end{array}} \right)$

Solution

(b) माना $\left[ {\begin{array}{*{20}{c}}a&a\\a&a\end{array}} \right]$ तत्समक अवयव है, तब                       

$\left[ {\begin{array}{*{20}{c}}x&x\\x&x\end{array}} \right]\left[ {\begin{array}{*{20}{c}}a&a\\a&a\end{array}} \right] = \left[ {\begin{array}{*{20}{c}}x&x\\x&x\end{array}} \right]$             

अर्थात $2ax = x \Rightarrow a = \frac{1}{2}$,           

 अत: तत्समक अवयव = $\frac{1}{2}\left[ {\begin{array}{*{20}{c}}1&1\\1&1\end{array}} \right]$.

Standard 12
Mathematics

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