Difference between revisions of "Quadratic Reciprocity Theorem"

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Quadratic reciprocity is a classic result of number theory.<\br>
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Quadratic reciprocity is a classic result of number theory.<br>
 
It is one of the most important theorems in the study of quadratic residues.
 
It is one of the most important theorems in the study of quadratic residues.
  
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If both <math>p</math> and <math>q</math> are of the form <math>4n+3</math>, then <math>\left(\frac{p}{q}\right)= -\left(\frac{q}{p}\right)</math>
 
If both <math>p</math> and <math>q</math> are of the form <math>4n+3</math>, then <math>\left(\frac{p}{q}\right)= -\left(\frac{q}{p}\right)</math>
  
Another way to state this is:<\br>
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Another way to state this is:<br>
 
<math>\left(\frac{p}{q}\right)\left(\frac{q}{p}\right)=(-1)^{\frac{p-1}{2}\frac{q-1}{2}}</math>
 
<math>\left(\frac{p}{q}\right)\left(\frac{q}{p}\right)=(-1)^{\frac{p-1}{2}\frac{q-1}{2}}</math>

Revision as of 20:53, 10 October 2011

Quadratic reciprocity is a classic result of number theory.
It is one of the most important theorems in the study of quadratic residues.

It states that $\left(\frac{p}{q}\right)= \left(\frac{q}{p}\right)$ for primes $p$ and $q$ greater than $2$ where both are not of the form $4n+3$ for some integer $n$. If both $p$ and $q$ are of the form $4n+3$, then $\left(\frac{p}{q}\right)= -\left(\frac{q}{p}\right)$

Another way to state this is:
$\left(\frac{p}{q}\right)\left(\frac{q}{p}\right)=(-1)^{\frac{p-1}{2}\frac{q-1}{2}}$