6mx²-4nxy+2x+2xy-x²+y-4
=(6m-1)x²+(2-4n)xy+2x-4
因为不含有2此项
所以
6m-1=0
2-4n=0
6m=1
4n=2
2n=1
所以:6m-2n+2=1-1+2=2