Originally Posted by

**CaptainBlack** The general cubic equation may be written:

x^3+a x^2 + b x + c=0

Make a change of variable y=x+u, and choose u so that the coefficient of y

is zero (this will entail solving a quadratic). then make another change of

variable n=ky so that the equation has the form:

An^3+An^2+C=0

Then divide through by A to get:

n^3+n^2=C/A

(the only problem that I can see is that the quadratic is not guaranteed to have real roots, and complex roots would have stopped a Babalonian in their tracks)

RonL