8. The solution set of the inequality
$$
\frac{4 x^{2}}{(1-\sqrt{1+2 x})^{2}}<2 x+9
$$

is $\qquad$ .
8. $\left[-\frac{1}{2}, 0\right) \cup\left(0, \frac{45}{8}\right)$.

Obviously, $x \geqslant-\frac{1}{2}, x \neq 0$.
The original inequality simplifies to
$$
x^{2}(8 x-45)<0 \Rightarrow x<\frac{45}{8} \text {. }
$$

Therefore, $-\frac{1}{2} \leqslant x<0$ or $0<x<\frac{45}{8}$.