$A = \left[ {\begin{array}{*{20}{c}}1&0&0\\0&1&1\\0&{ - 2}&4\end{array}} \right];\,\,I = \left[ {\begin{array}{*{20}{c}}1&0&0\\0&1&0\\0&0&1\end{array}} \right] ; {A^{ - 1}} = \frac{1}{6}[{A^2} + cA + dI]$ કે જ્યાં $c,d \in R$, તો $(c,d) =\ . ....... .$
A $(6, 11)$ B $(6, -11)$ C $(-6, 11)$ D $(-6, -11)$ Download our app for free and get started Solution
C $(-6, 11)$
Given $A = \left[ {\begin{array}{*{20}{c}}1&0&0\\0&1&1\\0&{ - 2}&4\end{array}} \right],\,\,{A^{ - 1}} = \frac{1}{6}\left[ {\begin{array}{*{20}{c}}6&0&0\\0&4&{ - 1}\\0&2&1\end{array}} \right]$
${A^2} = \left[ {\begin{array}{*{20}{c}}1&0&0\\0&1&1\\0&{ - 2}&4\end{array}} \right]\,\left[ {\begin{array}{*{20}{c}}1&0&0\\0&1&1\\0&{ - 2}&4\end{array}} \right]\, $
$= \left[ {\begin{array}{*{20}{c}}1&0&0\\0&{ - 1}&5\\0&{ - 10}&{14}\end{array}} \right]$
$cA = \left[ {\begin{array}{*{20}{c}}c&0&0\\0&c&c\\0&{ - 2c}&{4c}\end{array}} \right]\,$; $dI = \left[ {\begin{array}{*{20}{c}}d&0&0\\0&d&0\\0&0&d\end{array}} \right]$
$\therefore $ By ${A^{ - 1}} = \frac{1}{6}[{A^2} + cA + dI]$
$ 6 = 1 + c + d, ($By equality of matrices$)$
$\therefore (-6,11)$ satisfy the relation.