\[x^{2} + 8ax - 15a + 1 = 0\]
\[x^{2} + 8ax - (15a - 1) = 0\]
\[Уравнение\ имеет\ два\ корня\ \]
\[при\ D > 0:\]
\[D = 64a^{2} + 4(15a - 1) =\]
\[= 64a^{2} + 60a - 4;\]
\[64a^{2} + 60a - 4 > 0\ \ \ \ |\ :4\]
\[16a^{2} + 15a - 1 > 0\]
\[D = 225 + 64 = 289 = 17^{2}\]
\[a_{1} = \frac{- 15 + 17}{32} = \frac{2}{32} = \frac{1}{16};\]
\[a_{2} = \frac{- 15 - 17}{32} = - \frac{32}{32} = - 1.\]
\[Ответ:при\ a = - 1;\ \ a = \frac{1}{16}.\]