Hi,

let $\displaystyle T$ be the splitting field over $\displaystyle \mathbb Q$ of a polynomial $\displaystyle f(x)=x^n+\sum_{i=0}^{n-1} a_i x^i \in \mathbb Q[x]$, where $\displaystyle a_i$ are integral for the prime numbers 2 and 3 and let $\displaystyle f \text{ mod }3 $ be irreducible.

Now it is said, that 3 is unramified in $\displaystyle T$.

Please can you explain that to me? I don't understand it.

Bye,
Alexander