Example 2 Find the intervals in which the function y = x 3 3 x 2 + 8 is increasing and decreasing, where the stationary points are at x = 0 and x = 2.

, , Increasing or Decreasing Returns to Scale in the Constant Elasticity of Substitution Production Function, The Review of Economics and Statistics, Vol. 51, No. 1 (Feb., 1969), pp. 84-90 ...