A quantity involving primitive cube roots of unity which can be used to solve the cubic equation.
Lagrange Resolvent
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References
Faucette, W. M. "A Geometric Interpretation of the Solution of the General Quartic Polynomial." Amer. Math. Monthly 103, 51-57, 1996.Referenced on Wolfram|Alpha
Lagrange ResolventCite this as:
Weisstein, Eric W. "Lagrange Resolvent." From MathWorld--A Wolfram Web Resource. https://mathworld.wolfram.com/LagrangeResolvent.html