Given, M = \left[ \begin{cases}0 & 1 & a \\ 1 & 2 & 3 \\ 3 & b & 1\end{cases}\right] ...(i)adj\left(M\right) = \left[ \begin{cases}- 1 & 1 & - 1 \\ 8 & - 6 & 2 \\ - 5 & 3 & - 1\end{cases}\right] ...(ii) Option ( A ) ( A ) ( A ) : Now from matrix M M M ( a d j M ) 11 = 2 − 3 b {\left(adjM\right)}_{11} = 2 - 3b ( a d j M ) 11 = 2 − 3 b As given 2 − 3 b = − 1 ⇒ b = 1 2 - 3b = - 1 ⇒ b = 1 2 − 3 b = − 1 ⇒ b = 1
Similarly, a = 2 a = 2 a = 2
a + b = 3 a + b = 3 a + b = 3 Using the values of a a n d a and aan d bi n m a t r i x in matrix inma t r i x M ⇒ | M | = - 2< b r / > <br /> < b r / > | adj\left({M}^{2}\right) | = | {M}^{2}{|}^{2} = | M{|}^{4} = 16< b r / > N o w , <br />Now, < b r / > N o w , {M}^{- 1} = \dfrac{adjM}{\left|M\right|}< b r / > <br /> < b r / > adjM = \left|M\right|{M}^{- 1}< b r / > <br /> < b r / > adj ( M ) = - 2{M}^{- 1}< b r / > <br /> < b r / > {\left(adj\left(M\right)\right)}^{- 1} = - \dfrac{1}{2}{\left({M}^{- 1}\right)}^{- 1}( ( K A ) − 1 = 1 K A − 1 ) \left({\left(KA\right)}^{- 1} = \dfrac{1}{K}{A}^{- 1}\right) ( ( K A ) − 1 = K 1 A − 1 ) ( a d j ( M ) ) − 1 = − M 2 {( adj ( M ) )}^{- 1} = \dfrac{- M}{2} ( a d j ( M )) − 1 = 2 − M and a d j ( M − 1 ) = ( M − 1 ) − 1 ∣ M − 1 ∣ adj ( {M}^{- 1} ) = {( {M}^{- 1} )}^{- 1} | {M}^{- 1} | a d j ( M − 1 ) = ( M − 1 ) − 1 ∣ M − 1 ∣ \left(adjA = \left|A\right|{A}^{1}\right)< b r / > <br /> < b r / > adj\left({M}^{- 1}\right) = \dfrac{M}{\left|M\right|}( ∣ A − 1 ∣ = 1 ∣ A ∣ ) \left(\left|{A}^{- 1}\right| = \dfrac{1}{\left|A\right|}\right) ( A − 1 = ∣ A ∣ 1 ) a d j ( M − 1 ) = − M 2 adj\left({M}^{- 1}\right) = - \dfrac{M}{2} a d j ( M − 1 ) = − 2 M ...(iii) From (iii) and (iv)( a d j ( M ) − 1 + ( a d j ( M − 1 ) ) = − M ( adj{\left(M\right)}^{- 1} + \left(adj\left({M}^{- 1}\right)\right) = - M ( a d j ( M ) − 1 + ( a d j ( M − 1 ) ) = − M Option ( D ) ( D ) ( D ) :MX = B\left(whenx = \left[ α β γ \begin{array}{ll}\alpha \\ \beta \\ \gamma\end{array} α β γ \right]andB = \left[ 1 2 3 \begin{array}{ll}1 \\ 2 \\ 3\end{array} 1 2 3 \right]\right) X = M − 1 ( B ) X = {M}^{- 1} ( B ) X = M − 1 ( B ) X = a d j ( M ) ∣ M ∣ B X = \dfrac{adj\left(M\right)}{\left|M\right|}B X = ∣ M ∣ a d j ( M ) B \left[α β γ \begin{array}{ll}\alpha \\ \beta \\ \gamma\end{array} α β γ \right] = - \dfrac{1}{2}\left[{ − 1 1 − 1 8 − 6 2 − 5 3 − 1 \begin{cases}- 1 & 1 & - 1 \\ 8 & - 6 & 2 \\ - 5 & 3 & - 1\end{cases} ⎩ ⎨ ⎧ − 1 8 − 5 1 − 6 3 − 1 2 − 1 \right]\left[1 2 3 \begin{array}{ll}1 \\ 2 \\ 3\end{array} 1 2 3 \right]< b r / > <br /> < b r / > = - \dfrac{1}{2}\left[− 2 2 − 2 \begin{array}{ll}- 2 \\ 2 \\ - 2\end{array} − 2 2 − 2 \right]<br />\left[ α β γ \begin{array}{ll}\alpha \\ \beta \\ \gamma\end{array} α β γ \right] = \left[ 1 − 1 1 \begin{array}{ll}1 \\ - 1 \\ 1\end{array} 1 − 1 1 \right] ∵ α = 1 β = − 1 γ = 1 ∵ \alpha = 1\beta = - 1\gamma = 1 ∵ α = 1 β = − 1 γ = 1 α − β + γ = 3 \alpha - \beta + \gamma = 3 α − β + γ = 3