If $A=\left[\begin{array}{ll}2 & 3 \\ 1 & 4\end{array}\right]$ and $B=\left[\begin{array}{cc}1 & -2 \\ 1 & 3\end{array}\right]$, then which of the following are incorrect? A. $|A|=5$ Choose the correct answer from the options given below: |
B, C only B, C, D only A, B only A, B, E only |
B, C only |
The correct answer is Option (1) - B, C only $|A|=2×4-3=5$ $|B|=3×1+(-2)×1=5$ $|3B|=3^2×|B|=45$ (A, D correct) for A → cofactors $C_{11}=4, C_{12}=-1$ $C_{21}=-3,C_{22}=2$ $Adj\,A=\left[\begin{array}{ll}4 & 3 \\ 1 & 2\end{array}\right]^T=\left[\begin{array}{ll}4 & -3 \\ -1 & 2\end{array}\right]$ (B incorrect) also $A(adj\,A)=5I$ (C incorrect) B already incorrect |