There is no quadratic term, and its coefficient is zero. Finish the original formula =(6m- 1)x? +(4n+2)xy+2x+y+4, the quadratic coefficient is zero, that is, (6m- 1)=0, 4n+2=0, and the solution is 6m= 1, n=- 1/2. So 6m-n+2=5/2.