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.

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- May 20th 2009, 03:46 PMmicky_577Proof 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 PMPlato
- May 20th 2009, 04:02 PMmicky_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 PMpickslides
I would argue that if n is a perfect square i.e $\displaystyle n=a^2$ then $\displaystyle n-1 = a^2-1 $ , now $\displaystyle a^2-1$ can be factored into $\displaystyle (a-1)(a+1)$ and in turn so can n-1 so it cannot be prime.

- May 20th 2009, 04:56 PMPlato
- May 20th 2009, 05:10 PMmicky_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.