\[2x^{2} + nx - (18 - x) = 0\]
\[Пусть\ a\ и\ ( - a) - корни\ \]
\[данного\ уравнения.\]
\[Получаем:\]
\[1)\ 2a^{2} + na - (18 - a) = 0\]
\[2)\ 2a^{2} - na - (18 + a) = 0\]
\[na - (18 - a) + na + (18 + a) =\]
\[= 0\]
\[2na + 2a = 0\]
\[n + 1 = 0\]
\[n = - 1.\]
\[Ответ:при\ n = - 1.\]