Answer to Question #196378 in Linear Algebra for Juwehan

Question

Use the cofactor expansion to determine

{{2000}{3120}{2-504}{1303}}

Answer 1

$\begin{vmatrix} 2 & 0&0&0 \\ 3 &1&2&0\\ 2&-5&0&4\\ 1&3&0&3\end{vmatrix}=2\begin{vmatrix} 1 & 2&0 \\ -5 & 0&4\\ 3&0&3 \end{vmatrix}=2(-2)\begin{vmatrix} -5 & 4 \\ 3 & 3 \end{vmatrix}=-4(-15-12)=108.$