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Indigo5684
2025-09-30 13:19:29 -05:00
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commit 78c6ed9889
8 changed files with 29 additions and 29 deletions

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@@ -36,9 +36,9 @@ $$
where either $\deg r(x) < \deg g(x)$ or $r(x)$ is the zero polynomial.
**Collary**. Let $F$ be a field. Then, an element $\alpha \in F$ is a zero of $p(x) \ in F[x]$ if and only if $(x-\alpha)$ is a factor of $p(x)$.
**Corollary**. Let $F$ be a field. Then, an element $\alpha \in F$ is a zero of $p(x) \ in F[x]$ if and only if $(x-\alpha)$ is a factor of $p(x)$.
**Collary**. Let $F$ be a field. Then, a nonzero polynomial $p(x) \in F[x]$ with degree $n$ can have at most $n$ distinct zeros in $F$.
**Corollary**. Let $F$ be a field. Then, a nonzero polynomial $p(x) \in F[x]$ with degree $n$ can have at most $n$ distinct zeros in $F$.
**Definition**. A monic polynomial $d(x)$ is the *greatest common divisor* of polynomials $p(x), q(x) \in F[x]$ if $d(x)$ evenly divides both $p(x)$ and $q(x)$. We write $\gcd(p(x), q(x)) = d(x)$. This polynomial is unique.
@@ -52,7 +52,7 @@ where either $\deg r(x) < \deg g(x)$ or $r(x)$ is the zero polynomial.
**Lemma**. Gauss's Lemma. Let $p(x) \in \mathbb{Z}[x]$ be monic such that $p(x)$ factors into two polynomials $\alpha(x), \beta{x} \in \mathbb{Q}[x]$, with the degrees of both strictly less than the degree of $p(x)$. Then, there exists two polynomials $a(x), b(x) \in \mathbb{Z}[x]$ such that $p(x) = a(x)b(x)$, and $\deg \alpha(x) = \deg a(x)$ and $\deg \beta(x) = \deg b(x)$.
**Collary**. Let $p(x) \in \mathbb{Z}[x]$ be monic with constant term $a_0$. Then, if $p(x)$ has a zero in $\mathbb{Q}$, then it also has a zero $\alpha$ in $\mathbb[Z]$. Furthermore, $\alpha$ divides $a_0$.
**Corollary**. Let $p(x) \in \mathbb{Z}[x]$ be monic with constant term $a_0$. Then, if $p(x)$ has a zero in $\mathbb{Q}$, then it also has a zero $\alpha$ in $\mathbb[Z]$. Furthermore, $\alpha$ divides $a_0$.
**Theorem**. Eisenstein's Criterion. Let $p$ be prime, and suppose that