Tuesday, 12 February 2019

abstract algebra - Two number fields with trivial intersection, not linearly disjoint but....



Do there exist two finite extensions of Q, L=Q(α) and K=Q(β) such that LK=Q, the minimal polynomial μα(X)Q[X] of α over Q is not irreducible over K, but μα(β)0 ?



Answer



Sure. Let α=32, let γ be a nonreal cube root of 2, and let β=γ+1.


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