18. If
$$\left[ \begin{array} { l l l }
4 a ^ { 2 } & 4 a & 1 \\
4 b ^ { 2 } & 4 b & 1 \\
4 c ^ { 2 } & 4 c & 1
\end{array} \right] \left[ \begin{array} { c }
f ( - 1 ) \\
f ( 1 ) \\
f ( 2 )
\end{array} \right] = \left[ \begin{array} { l l l }
3 a ^ { 2 } & + & 3 a \\
3 b ^ { 2 } & + & 3 b \\
3 c ^ { 2 } & + & 3 c
\end{array} \right] ,$$
$f ( x )$ is a quadratic function and its maximum value occurs at a point $V$. $A$ is a point of intersection of $y = f ( x )$ with $x$-axis and point $B$ is such that chord $A B$ subtends a right angle at V . Find the area enclosed by $\mathrm { f } ( \mathrm { x } )$ and chord AB .