Let $A =\begin{bmatrix}1&2&1\\-1&3&2\\2&4&1\end{bmatrix}$ and $M_{ij}, A_{ij}$ respectively denote the minor, co-factor of an element $a_{ij}$ of matrix A, then which of the following are true? (A) $M_{22} = -1$ Choose the correct answer from the options given below: |
(A) and (B) only (A), (B), (C) and (E) only (A), (D) and (E) only (A), (C) and (E) only |
(A) and (B) only |
The correct answer is Option (1) → (A) and (B) only $A=\begin{pmatrix}1&2&1\\-1&3&2\\2&4&1\end{pmatrix}$ (A) $M_{22}$ Delete row $2$, column $2$ $M_{22}=\begin{vmatrix}1&1\\2&1\end{vmatrix}=1-2=-1$ True (B) $A_{23}$ $M_{23}=\begin{vmatrix}1&2\\2&4\end{vmatrix}=4-4=0$ $A_{23}=(-1)^{2+3}M_{23}=0$ True (C) $A_{32}$ $M_{32}=\begin{vmatrix}1&1\\-1&2\end{vmatrix}=2+1=3$ $A_{32}=(-1)^{3+2}\cdot3=-3\ne3$ False (D) $M_{23}=1$ $M_{23}=0$ False (E) $M_{32}=-3$ $M_{32}=3$ False The correct statements are (A) and (B). |