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In this paper we entertain a simple idea that the action of ghost freemassive gravity (in metric formulation) depends not on the full structure ofthe square root of a matrix but rather on its invariants given by elementarysymmetric polynomials of the eigenvalues. In particular, we show how one canconstruct the quadratic action around Minkowski spacetime without ever takingthe square root of the perturbed matrix. The method is however absolutelygeneric. And it also contains full information on possible non-standard squareroots coming from intrinsic non-uniqueness of the procedure. In passing, wemention some hard problems of those apocryphal square roots in the standardapproach which might be better tackled with our method. Futher details of thelatter are deferred to a separate paper.

Dealing with ghost-free massive gravity without explicit square roots of matrices