Discussion Forum

1)

If $A=\begin{bmatrix}1 & 1&0 \\2 & 1&5\\1&2&1 \end{bmatrix}$ , then

$a_{11}A_{21}+a_{12}A_{22}+a_{13}A_{23}$  is equal to

Answer:

Option B

Explanation:

Given , $A=\begin{bmatrix}1 & 1&0 \\2 & 1&5\\1&2&1 \end{bmatrix}$

We know that, the sum of the product of element other than the corresponding cofactor is zero.

$\therefore$    $a_{11}A_{21}+a_{12}A_{22}+a_{13}A_{23}$ =0