Решите уравнение: x^2+7*корень из (x^2 )-18=0.

\[x² + 7\sqrt{x^{2}} - 18 = 0\]

\[x^{2} + 7|x| - 18 = 0\]

\[D = 7^{2} - 4 \cdot 1 \cdot ( - 18) =\]

\[= 49 + 72 = 121\]

\[x_{1} = \frac{- 7 + \sqrt{121}}{2} = \frac{- 7 + 11}{2} =\]

\[= \frac{4}{2} = 2\]

\[x_{2} = \frac{- 7 - \sqrt{121}}{2} = \frac{- 7 - 11}{2} =\]

\[= - \frac{18}{2} = - 9\ (не\ подходит).\]

\[D = ( - 7)^{2} - 4 \cdot 1 \cdot ( - 18) =\]

\[= 49 + 72 = 121\]

\[x_{1} = \frac{7 + \sqrt{121}}{2} = \frac{7 + 11}{2} =\]

\[= \frac{18}{2} = 9\ (не\ подходит)\]

\[x_{2} = \frac{7 - \sqrt{121}}{2} = \frac{7 - 11}{2} =\]

\[= - \frac{4}{2} = - 2\]

\[Ответ:2;\ - 2.\]