Re: a prime number question
- From: "Eric J. Wingler" <wingler@xxxxxxxxxxxx>
- Date: Tue, 24 Jan 2006 10:28:40 -0500
Calculating mod 29, you get
3^7 - 2^7 = 3*(3^3)^2 - 2^7
= 3*2^2 - 2^7
= 4*(3 - 2^5)
= 0 (mod 29).
Hence 3^7 - 2^7 is divisible by 29.
________________________________
Eric J. Wingler (wingler@xxxxxxxxxxxx)
Dept. of Mathematics and Statistics
Youngstown State University
One University Plaza
Youngstown, OH 44555-0001
330-941-1817
"gilevgi" <gilevgi@xxxxxxxxx> wrote in message
news:1138102507.291062.248130@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
> Can you prove that 3^7-2^7 is not prime? I calculated it. but i want to
> know the proof without calculating 3^7 and 2^7.
>
> thanks in advance.
>
.
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