If $K/\mathbb{Q}$ is an extension of degree $2$, then necessarily it is of the form $\mathbb{Q}(\sqrt{d})$. So, I am wondering if a similar philosophy holds for extension over $\mathbb{Q}$ of degree 3.
2026-03-25 09:10:34.1774429834
Is any rational extension of degree 3 of the form $\mathbb{Q}(\sqrt[3]{d})$?
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Your answer I think should be negative because if, for example, $\theta$ is the real root of $x^3+x+1=0$ then $K=\mathbb Q(\theta)$ is of degree $3$ but $\theta\approx -0.6823$ being such that $\theta^3+\theta+1=0$ is not of the form you asked.