① [(x2+18x+72)÷(x+12)-（x2+5x-6)÷（x-1）]×（x3-2x2-x+1)=[(x+6)(x+12)÷(x+12)-(x+6)(x-1)÷(x-1)]×（x3-2x2-x+1)=[(x+6)-(x+6)]×（x3-2x2-x+1)=0② 5.81×10^12-5×10^10---------------------------(-1.25×10^4)×(1.6×10^6) =-10^10×(581-5)÷[(10^4×10^6)×(1.25×0.8×2)]=-576÷2=-288
