If $$5f(x) + 4f\left(\frac{1}{x}\right) = x^2 - 2$$, $$\forall x \neq 0$$ and $$y = 9x^2 f(x)$$, then $$y$$ is strictly increasing in:

A

$$\left(0, \frac{1}{\sqrt{5}}\right) \cup \left(\frac{1}{\sqrt{5}}, \infty\right)$$

B

$$\left(-\frac{1}{\sqrt{5}}, 0\right) \cup \left(\frac{1}{\sqrt{5}}, \infty\right)$$

C

$$\left(-\frac{1}{\sqrt{5}}, 0\right) \cup \left(0, \frac{1}{\sqrt{5}}\right)$$

D

$$\left(-\infty, \frac{1}{\sqrt{5}}\right) \cup \left(0, \frac{1}{\sqrt{5}}\right)$$