1/3a²n-(-7an)+(-1)²n+1an-(2/5a2n)-5an(n为整数)
=1/3a²n+7an+n+an-2/5a2n-5an
=-1/15a²n+3an+n
9m²+[4m²-3m-(2m²-6m)]
=11m²+3m