From 0e9d69b8d9ece72a1af266d5bb2473f9fee604d8 Mon Sep 17 00:00:00 2001 From: jxu <7989982+jxu@users.noreply.github.com> Date: Sun, 13 Oct 2024 21:07:36 -0400 Subject: [PATCH 1/3] =?UTF-8?q?linear-diophantine:=20add=20B=C3=A9zout's?= =?UTF-8?q?=20lemma=20and=20slightly=20reformat=20mathjax?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/algebra/linear-diophantine-equation.md | 16 ++++++++++++---- 1 file changed, 12 insertions(+), 4 deletions(-) diff --git a/src/algebra/linear-diophantine-equation.md b/src/algebra/linear-diophantine-equation.md index 047067c59..2364e99fa 100644 --- a/src/algebra/linear-diophantine-equation.md +++ b/src/algebra/linear-diophantine-equation.md @@ -23,14 +23,22 @@ In this article, we consider several classical problems on these equations: A degenerate case that need to be taken care of is when $a = b = 0$. It is easy to see that we either have no solutions or infinitely many solutions, depending on whether $c = 0$ or not. In the rest of this article, we will ignore this case. +## Bézout's lemma + +Bézout's lemma (also called Bézout's identity) is a useful result that can be used to understand and prove the following analytic solution. + +> Let $g = \gcd(a,b)$. Then there exist integers $x,y$ such that $ax + by = g$. +> +> Moreover, $g$ is the least such positive integer that can be written as $ax + by$; all integers of the form $ax + by$ are multiples of $g$. + ## Analytic solution When $a \neq 0$ and $b \neq 0$, the equation $ax+by=c$ can be equivalently treated as either of the following: -\begin{gather} -ax \equiv c \pmod b,\newline -by \equiv c \pmod a. -\end{gather} +\begin{align} +ax &\equiv c \pmod b \\ +by &\equiv c \pmod a +\end{align} Without loss of generality, assume that $b \neq 0$ and consider the first equation. When $a$ and $b$ are co-prime, the solution to it is given as From 5617b117b8888e7e28ba27d53f63446c7285c9e0 Mon Sep 17 00:00:00 2001 From: jxu <7989982+jxu@users.noreply.github.com> Date: Sun, 13 Oct 2024 21:29:12 -0400 Subject: [PATCH 2/3] linear-diophantine: move identity --- src/algebra/linear-diophantine-equation.md | 14 ++++++-------- 1 file changed, 6 insertions(+), 8 deletions(-) diff --git a/src/algebra/linear-diophantine-equation.md b/src/algebra/linear-diophantine-equation.md index 2364e99fa..852d0f255 100644 --- a/src/algebra/linear-diophantine-equation.md +++ b/src/algebra/linear-diophantine-equation.md @@ -23,14 +23,6 @@ In this article, we consider several classical problems on these equations: A degenerate case that need to be taken care of is when $a = b = 0$. It is easy to see that we either have no solutions or infinitely many solutions, depending on whether $c = 0$ or not. In the rest of this article, we will ignore this case. -## Bézout's lemma - -Bézout's lemma (also called Bézout's identity) is a useful result that can be used to understand and prove the following analytic solution. - -> Let $g = \gcd(a,b)$. Then there exist integers $x,y$ such that $ax + by = g$. -> -> Moreover, $g$ is the least such positive integer that can be written as $ax + by$; all integers of the form $ax + by$ are multiples of $g$. - ## Analytic solution When $a \neq 0$ and $b \neq 0$, the equation $ax+by=c$ can be equivalently treated as either of the following: @@ -59,6 +51,12 @@ y = \frac{c-ax}{b}. ## Algorithmic solution +**Bézout's lemma** (also called Bézout's identity) is a useful result that can be used to understand and prove the following solution. + +> Let $g = \gcd(a,b)$. Then there exist integers $x,y$ such that $ax + by = g$. +> +> Moreover, $g$ is the least such positive integer that can be written as $ax + by$; all integers of the form $ax + by$ are multiples of $g$. + To find one solution of the Diophantine equation with 2 unknowns, you can use the [Extended Euclidean algorithm](extended-euclid-algorithm.md). First, assume that $a$ and $b$ are non-negative. When we apply Extended Euclidean algorithm for $a$ and $b$, we can find their greatest common divisor $g$ and 2 numbers $x_g$ and $y_g$ such that: $$a x_g + b y_g = g$$ From b1ba5990e50b1c63121750a8891218c8c4636b8f Mon Sep 17 00:00:00 2001 From: jxu <7989982+jxu@users.noreply.github.com> Date: Mon, 14 Oct 2024 13:45:38 -0400 Subject: [PATCH 3/3] =?UTF-8?q?linear-diophantine:=20reword=20B=C3=A9zout?= =?UTF-8?q?=20and=20explain=20all=20solutions?= MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit --- src/algebra/linear-diophantine-equation.md | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/algebra/linear-diophantine-equation.md b/src/algebra/linear-diophantine-equation.md index 852d0f255..3f4ede86c 100644 --- a/src/algebra/linear-diophantine-equation.md +++ b/src/algebra/linear-diophantine-equation.md @@ -51,7 +51,7 @@ y = \frac{c-ax}{b}. ## Algorithmic solution -**Bézout's lemma** (also called Bézout's identity) is a useful result that can be used to understand and prove the following solution. +**Bézout's lemma** (also called Bézout's identity) is a useful result that can be used to understand the following solution. > Let $g = \gcd(a,b)$. Then there exist integers $x,y$ such that $ax + by = g$. > @@ -125,7 +125,7 @@ $$y = y_0 - k \cdot \frac{a}{g}$$ are solutions of the given Diophantine equation. -Moreover, this is the set of all possible solutions of the given Diophantine equation. +Since the equation is linear, all solutions lie on the same line, and by the definition of $g$ this is the set of all possible solutions of the given Diophantine equation. ## Finding the number of solutions and the solutions in a given interval pFad - Phonifier reborn

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