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