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Ecuatie in numere intregi

Posted: Tue Apr 14, 2009 7:14 am
by Aelius Pop
Determinati numerele naturale \( x \) si \( y \) care satisfac ecuatia.

\( y^2 \) + \( (x+1)^2 \)=\( x^2 \)+\( (y+1)^2 \)=\( k^2 \)
\( k\in\mathbb{N} \)

Posted: Wed Apr 15, 2009 7:39 pm
by salazar
Folosim forumula:
\( (a+b)^2=a^2+2ab+b^2 \) si obtinem:
\( y^2+x^2+2x+1=x^2+y^2+2y+1=k \),
\( 2x=2y=k \)
\( x=y=k \), oricare ar fi \( x,y,k\in N \).

Posted: Wed Apr 15, 2009 9:45 pm
by Aelius Pop
Imi cer scuze pt eroarea comisa. Am editat enuntul. Acum e \( k^2 \) in loc de \( k \).