a
$\therefore \sum \mathrm{a}^{2}+\sum \mathrm{ab} \leq 0 $
$\Rightarrow(\mathrm{a}+\mathrm{b})^{2}+(\mathrm{b}+\mathrm{c})^{2}+(\mathrm{c}+\mathrm{a})^{2} \leq 0$
$\Rightarrow \mathrm{a}+\mathrm{b}=0, \mathrm{b}+\mathrm{c}=0, \mathrm{c}+\mathrm{a}=0$
$\Rightarrow \mathrm{a}=\mathrm{b}=\mathrm{c}=0$
$\therefore \left|\begin{array}{lll}{4} & {0} & {1} \\ {1} & {4} & {0} \\ {0} & {1} & {4}\end{array}\right|=65$