IMO Shortlist 2001 problem N5


Kvaliteta:
  Avg: 0,0
Težina:
  Avg: 8,0
Dodao/la: arhiva
2. travnja 2012.
LaTeX PDF
Let a > b > c > d be positive integers and suppose that ac + bd = (b+d+a-c)(b+d-a+c). Prove that ab + cd is not prime.
Izvor: Međunarodna matematička olimpijada, shortlist 2001