The conditions for cubic equations, to have 3 real roots and 2 of the roots lie in the closed interval $[-1, 1]$ are given. These conditions are visualized. This question arises in physics in e.g. the theory of tops.

翻译：本文给出了三次方程具有三个实根、且其中两个根位于闭区间 $[-1, 1]$ 内的条件。这些条件通过可视化方式呈现。该问题在物理学中（例如陀螺理论中）有所应用。