You are factoring a 3-degree polynomial, not analytically easy.
The best I can do is:
syms k1 k2 k3 x real
assume(k1 ~= 0)
assume(k2 ~= 0)
assume(k3 ~= 0)
Eqn = 1 + k1*x + k2*x^2 + k3*x^3;
F1 = solve(Eqn == 0, x, 'MaxDegree',2, 'Real',1);
F1v = vpa(F1,3);
abc = vpa(simplify(F1v, 'steps', 30), 3) % ‘a’, ‘b’, ‘c’ Coefficients
Simplifying the result or attempting to find subexpressions that would make it more tractable are not possible. No worries about the warning, but it is instructive.
