Question

The value of $\left|\begin{array}{ccc}41& 1& 5\\ 79& 7& 9\\ 29& 5& 3\end{array}\right|$ is:

• A. $5$
• B. $3$
• C. $1$
• D. $0$

Answer 1

The correct option is D $0$

$\Delta =\left|\begin{array}{ccc}41& 1& 5\\ 79& 7& 9\\ 29& 5& 3\end{array}\right|$
Applying $C_1\to C_1+(-8)C_3$, we get
$\Delta =\left|\begin{array}{ccc}1& 1& 5\\ 7& 7& 9\\ 5& 5& 3\end{array}\right|$
$\because C_1$ and $C_2$ are identical, $\Delta =0$