Вопрос:

Ответ:

\[x^{2} + \frac{9}{x^{2}} = 10\]

\[\left( x + \frac{3}{x} \right)^{2} - 6 = 10\]

\[\left( x + \frac{3}{x} \right)^{2} = 16\]

\[x + \frac{3}{x} = \pm 4.\ \]