How do you solve #x^3+x^2-10x+8>=0#?
Sum of the coefficients = 0. So, x-1 is a factor of the cubic. The other
quadratic factor is
The cubic (y) is 0, at x = -4, 1. or 2#.
Also, this implies that the cubic has to be < 0 beyond, before
reaching the third zero x = 2, to become positive once again...