Proof Method and strategy

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May 20th 2009, 03:46 PM
micky_577

Proof Method and strategy

Hi,

I am not able to solve this by proper method. Please someone help.

Show that if n is perfect square then n-1 is not prime number for all interger n>4.

Thanks in advance.
May 20th 2009, 03:55 PM
Plato

Quote:

Originally Posted by micky_577

Show that if n is perfect square then n-1 is not prime number for all interger n>4.

Do you know this web-page?
May 20th 2009, 04:02 PM
micky_577

Buddy,

I did not understand that. Is'nt prefect number is different than perfect squre? Please help me solve the question.

Thanks
May 20th 2009, 04:06 PM
pickslides

I would argue that if n is a perfect square i.e $n=a^2$ then $n-1 = a^2-1$ , now $a^2-1$ can be factored into $(a-1)(a+1)$ and in turn so can n-1 so it cannot be prime.
May 20th 2009, 04:56 PM
Plato

Quote:

Originally Posted by micky_577

Buddy,
I did not understand that. Is'nt prefect number is different than perfect squre? Please help me solve the question.

First of all, I doubt that I am your ‘buddy’. I have no idea who you could be.
From this reply it is clear that you don’t even understand your own question.
May 20th 2009, 05:10 PM
micky_577

Please accept my sincere apology Plato. You are really correct in saying that I really did not understand question but I am trying learn man.

Thank you very much for your help.

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