Question

HElp Please its Pre-Calculus Matrix

Answer 1

The determinant is C. -541.

Using a cofactor expansion along the first row:

`\begin{vmatrix}-8&-4&-1\\1&7&-3\\8&9&9\end{vmatrix} = -8\begin{vmatrix}7&-3\\9&9\end{vmatrix} + 4\begin{vmatrix}1&-3\\8&9\end{vmatrix} - \begin{vmatrix}1&7\\8&9\end{vmatrix} \\\\= -8(7*9-(-3)*9) + 4(1*9-(-3)*8) - (1*9-7*8) \\\\ = -8(63+27) + 4(9+24) - (9-56)\\\\= \boxed{-541}`