Has any one found a general analytic solution for third order polynomial roots that has been tested and shown to work? I have used different solutions from two different texts. When I test the solutions numerically using MathCAD, they both fail to yield zero when the roots are plugged into the original unfactored polynomial and the results are different from different texts. I've searched and corrected any errors that I made in the testing. I am beginning to wonder if this type of equation was ever really solved.
I found a file entitled CUBEPROOF.MCD when searching the messages but I can't seem to open it with MathCAD 2000.
I found a file entitled CUBEPROOF.MCD when searching the messages but I can't seem to open it with MathCAD 2000.