(3m+2n)的二次方-(3m-2n)的二次方
=(3m+2n+3m-2n)(3m+2n-3m+2n)
=6m*4n
=24mn
2008+2008的二次方-2009的二次方
=2008+(2008+2009)(2008-2009)
=2008-4017
=-2009