The Hamiltonian of a particle of mass m in one-dimension is H = \(\frac{{\rm{1}}}{{{\rm{2m}}}}{{\rm{p}}^{\rm{2}}}\,{\rm{ + }}\,{\rm{λ }}{\left| {\rm{x}} \right|^{\rm{3}}}\), where λ > 0 is a constant. If E₁ and E₂, respectively, denote the ground state energies of the particle for λ = 1 and λ = 2 (in appropriate units) the ratio E₂ / E₁ is best approximated by