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Let a<sub>1</sub>=a<sub>1</sub> and a<sub>2</sub>a<sub>3</sub>...a<sub>n</sub>=b<sub>1</sub>
  
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If p is a prime and divides a<sub>1</sub>a<sub>2</sub>a<sub>3</sub>...a<sub>n</sub>, then p divides a<sub>1</sub>b<sub>1</sub>
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If p is a prime that divides a<sub>1</sub>b<sub>1</sub>, then p divides a<sub>1</sub> or b<sub>1</sub>
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Let's say p does not divide a<sub>1</sub>, then gcd(p,a<sub>1</sub>)=1
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This means that there exists x and y for which the equation xp+ya<sub>1</sub>=1 holds
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Let's multiply both sides of this equation by b<sub>1</sub>:
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xpb<sub>1</sub>+ya<sub>1</sub>b<sub>1</sub>=b<sub>1</sub>
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By induction, p divides a<sub>1</sub>b<sub>1</sub> and let a<sub>1</sub>b<sub>1</sub>=kp. Let's divide the equation above by p:
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xb<sub>1</sub>+yk=b<sub>1</sub>/p
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If the LHS of the equation can be divided by p, the RHS of the equation can be divided by p also. Then, b<sub>1</sub> can be divided by p.
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Next, we let b<sub>2</sub>=a<sub>3</sub>a<sub>4</sub>...a<sub>n</sub> and repeat the process above. Eventually, we will find the a<sub>i</sub> for some i, which can be divided by p.
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-Ozgur

Revision as of 13:43, 7 September 2008

Let a1=a1 and a2a3...an=b1

If p is a prime and divides a1a2a3...an, then p divides a1b1

If p is a prime that divides a1b1, then p divides a1 or b1

Let's say p does not divide a1, then gcd(p,a1)=1

This means that there exists x and y for which the equation xp+ya1=1 holds

Let's multiply both sides of this equation by b1:

xpb1+ya1b1=b1

By induction, p divides a1b1 and let a1b1=kp. Let's divide the equation above by p:

xb1+yk=b1/p

If the LHS of the equation can be divided by p, the RHS of the equation can be divided by p also. Then, b1 can be divided by p.

Next, we let b2=a3a4...an and repeat the process above. Eventually, we will find the ai for some i, which can be divided by p.

-Ozgur

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