$$\\8x^3+4x^2-4x-1=0\\$$
this one is not jumping out at me. ![]()
Here is the graph showing the 3 real solutions
https://www.desmos.com/calculator/xhxudxv72l
and
$$y^3+4y^2+3y-1=0$$
this one is not jumping out at me either. ![]()
https://www.desmos.com/calculator/b5cmcqjhv0
You could use Newton's method of approximating roots to get the answers. :)
Do you know about that?