3a²b-[2a²b-(2abc-a²c)-4a²c]-abc
=3a²b-2a²b+2abc-a²c+4a²c-abc
=a²b+abc+3a²c
=(-4)²*(-3)+(-4)*(-3)*1+3*(-4)²
=-48+12+48
=12确定对？确定