I should mention that the following is the solution I have for a quartic: (as, for all I know, different forms exist...)

Solve .

Transform this equation to by the usual transformation .

Denote the three roots of the equation

(Note: I hope this is right as I had to correct the coefficient of the z^2 term in my book.)

as , , and .

Then the 4 solutions to the y equation above will be:

-Dan