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Revision difference : rational root theorem
Version 5 Version 4
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Consider the polynomial Consider the polynomial
$$p(x)=a_nx^n + a_{n-1}x^{n-1}+\cdots+a_1x+a_0$$ $$p(x)=a_nx^n + a_{n-1}x^{n-1}+\cdots+a_1x+a_0$$
where all the coefficients $a_i$ are integers. where all the coefficients $a_i$ are integers.
If $p(x)$ has a rational root $p/q$ where $\gcd(p,q)=1$, then If $p(x)$ has a rational root $p/q$ where $\gcd(p,q)=1$, then
$p| a_0$ and $q| a_n$. $p| a_0$ and $q| a_n$.
This theorem is a special case of a result about monic polynomials whose coefficients belong to a unique factorization domain. The theorem then states that any root in the fraction field is also in the base domain. This theorem is a special case of a result about monic polynomials whose coefficients belong to a unique factorization domain. The theorem then states that any root in the fraction field is also in the base domain.