Răspuns :
2009x2008-2008x2007-2x2006 =
= 2008 × (2009 - 2007) - 2×2006 =
= 2008 × 2 - 2 × 2006 =
= 2 × (2008 - 2006) =
= 2 × 2 =
= 4
= 2008 × (2009 - 2007) - 2×2006 =
= 2008 × 2 - 2 × 2006 =
= 2 × (2008 - 2006) =
= 2 × 2 =
= 4