Let $A=\begin{bmatrix}2&-3&4\\0&1&5\\-4&2&3\end{bmatrix}$, and $a_{ij}$ be any element of matrix A, $i, j ∈ \{1,2,3\}$, then which of the following are TRUE? (A) Minor of $a_{23} = 16$ Choose the correct answer from the options given below: |
(A) and (C) only (B) and (C) only (B), (D) and (E) only (A), (C) and (E) only |
(B), (D) and (E) only |
The correct answer is Option (3) → (B), (D) and (E) only $A=\begin{pmatrix}2&-3&4\\0&1&5\\-4&2&3\end{pmatrix}$ Minor of $a_{23}$ Delete row $2$ and column $3$ $M_{23}=\begin{vmatrix}2&-3\\-4&2\end{vmatrix}=2(2)-(-3)(-4)$ $=4-12=-8$ Hence (B) is true, (A) is false Cofactor of $a_{23}$ $A_{23}=(-1)^{2+3}M_{23}=-(-8)=8$ Hence (D) is true, (C) is false Cofactor of $a_{13}$ Delete row $1$ and column $3$ $M_{13}=\begin{vmatrix}0&1\\-4&2\end{vmatrix}=0(2)-1(-4)=4$ $A_{13}=(-1)^{1+3}M_{13}=4$ Hence (E) is true The correct options are (B), (D) and (E). |