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Find all units of $S$, where $S$ is the set of polynomials in $\mathbb{Q}[x]$ whose coefficient of $x$ is $0$. I think the units are $\mathbb{Q} \setminus \{0\}$. Is that correct?

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    What is $Q$? Do you mean the rational numbers, $\mathbb{Q}$?2012-04-04
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    Q means the set of rational numbers2012-04-04
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    @TheChaz: That was an edit made after Brandon's comment.2012-04-04
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    "units of $S$, where $S$ is the set of ..." is a somewhat unusual use of the terminology -- usually in "units *of* $X$", $X$ is a ring; otherwise one would say something like "the units of $\mathbb Q[x]$ that lie in $S$". But it so happens that $S$ is indeed a ring, so you could say "Find all units of $S$, where $S$ is the ring of ...".2012-04-04
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    so, what are the units then?2012-04-04
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    @max: You're right that the units are $\mathbb Q\setminus \{0\}$ -- but note the direction of the slash; "$/$" has a _different_ meaning in algebra. Now can you start a proof why this is true? We'll help you fill in the gaps where you get into trouble.2012-04-04
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    I think I got the proof. Thanks a lot.2012-04-04

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