n e N, and n = 5 (mod6). prove that n^2 + 2 is composite. Can someone give me a detailed, step by step proof of how to do this?? I'm completely confused when it comes to modular arithmetic

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- May 12th 2009, 10:20 PMqtpipiModular arithmetic HELP!!
n e N, and n = 5 (mod6). prove that n^2 + 2 is composite. Can someone give me a detailed, step by step proof of how to do this?? I'm completely confused when it comes to modular arithmetic

- May 13th 2009, 02:24 AMMoo
- May 13th 2009, 06:19 AMSoroban
Hello, qtpipi!

Another approach . . .

Quote:

Prove that is composite.

Let

. . Then: .

Therefore, is composite.

- May 16th 2009, 01:02 PMTheAbstractionist