Question

The cofactor of the element '4' in the determinant $\left| \begin{matrix} 1 & 3 & 5 & 1 \\ 2 & 3 & 4 & 2 \\ 8 & 0 & 1 & 1 \\ 0 & 2 & 1 & 1 \end{matrix} \right|$ is.

• A. 4
• B. 10
• C. – 10
• D. – 4

Answer 1

Answer: (B)

10

Answer 2

The cofactor of element 4, in the 2^nd row and $3^{rd}$ column is

$= ( - 1)^{2 + 3}\left| \begin{matrix} 1 & 3 & 1 \\ 8 & 0 & 1 \\ 0 & 2 & 1 \end{matrix} \right|$=– {1(– 2) – 3 (8 – 0)+ 1.16}

= 10.