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I have the following:

$$ab \pmod x = 1.$$

$a$ and $b$ are known. Is there an efficient procedure to find the largest possible value of $x$?

Edit: What if $a$ and $b$ are too large to factor efficiently though?

Juniven Acapulco
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Matt
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1 Answers1

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$ab-1\equiv0\pmod x$. So what's the largest factor of $ab-1$?

Mike
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