-2x^（3m+1)·y^(2n)*7x^(6-n)·y^(3-m)=-14x^(3m+1+6-n)·y^(2n+3-m)=-14x^(3m-n+7)·y^(2n-m+3)又因为它与x^11·y^5是同类项,所以相同底数的指数应该相同,所以3m-n+7=112n-m+3=5m=2n=2所以3m-2n=6-4=2...