(a)
On putting $x = 0,$we observe that the determinant becomes zero.
$\therefore\mathrm{\Delta} = \left| \begin{array}{r}
0\ –a\ - b \\
a\ \ \ \ 0\ - c \\
b\ \ \ \ \ c\ \ \ \ \ \ 0
\end{array} \right|$
$= a(bc) - b(ac) = 0$
Hence, $x = 0$ is a root of the given equation