Galois’s Great Theorem
We prove the converse of Theorem 74: Solvability of the Galois group of f(x) ∈F[x], where F is a field of characteristic 0, implies f(x) is solvable by radicals. We begin with some lemmas; the first one has a quaint name signifying its use as a device to get around the possible absence of roots of unity in the ground field.
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