2012×2011-2011×2010-2010×2009+2008×2008
=2011×(2012-2010)-2010×2009+2008×2008
=2011×2-2010×2009+2008×2008
=2011×2-2010×(2008+1)+2008×2008
=2011×2-2010×2008-2010+2008×2008
=2011×2-2008×(2010-2008)-2010
=2011×2-2008×2-2010
=(2011-2008)×2-2010
=3×2-2010
=-2004