8. Let the inequality $x^{4}+(a-2) x^{2}+a \geqslant 0$ hold for all real numbers $x$, the range of real number $a$ is $\qquad$ .
8. $a \geqslant 4-2 \sqrt{3}$.

Let $t=x^{2} \geqslant 0$, the original inequality becomes $t^{2}+(a-2) t+a \geqslant 0$. When $t \geqslant 0$, it holds. $\Delta \leqslant 0$ or $\left\{\begin{array}{l}\Delta \geqslant 0 \\ -\frac{a-2}{2} \geqslant 0,\end{array}\right.$