This polynomial is of degree six, but only of degree three in , and so the corresponding equation is solvable by the method described in the article about cubic function. By substituting the roots in the expression of the in terms of the , we obtain expression for the roots. In fact we obtain, apparently, several expressions, depending on the numbering of the roots of the cubic polynomial and of the signs given to their square roots. All these different expressions may be deduced from one of them by simply changing the numbering of the .