u(x) = -x^³ + 4x^². At the initial moment of time a body of mass 2g starts out from the point x₀ at a velocity of v₀ (cm/sec):

(a) x₀ = 1, v₀ = 1,

(b) x₀ = -2, v₀ = 1,

(c) x₀ = -2, v₀ = -1.

In each case investigate the nature of the motion (points at which the body stops, regions which the body cannot reach). In the case of stopping points, give at least a rough idea of their coordinates.