For example, to solve  ,  use the substitution    to get  ,  which is a depressed cubic equation.  Next, apply the "Ferro-Tartaglia" formula with and to get  .  Since    is a root,     must be a factor of  .  Dividing     into    gives  ,  which yields the remaining (duplicate) roots of   .  The solutions to    are obtained by recalling  , which yields the three roots    and  .

Exploration.

(c) 2006 John H. Mathews, Russell W. Howell