Question

Evaluate the determinant: $\left|\begin{array}{ccc}9& 1& 6\\ 3& 7& 4\\ 6& 2& 3\end{array}\right|$

Answer 1

$\left|\begin{array}{ccc}9& 1& 6\\ 3& 7& 4\\ 6& 2& 3\end{array}\right|$

$=9(21-8)-1(9-24)+6(6-42)$

$=117+15-216$

$=-84$