The product of the roots of the equation,  $9x^2-18\left|x\right|+5=0$  is 

$9x^2-18\left|x\right|+5=0$

$x^2-2\left|x\right|+\frac{5}{9}=0 then the two equations are$

$$\begin{gathered} x^2-2x+\frac{5}{9}=0, x^2+2x+\frac{5}{9}=0 it becomes \\ (x^2-2x+\frac{5}{9}) (x^2+2x+\frac{5}{9})=0 \\ product of roots = \frac{25}{81} \end{gathered}$$