9.9x8.6+0.86=9.9x8.6+0.1*8.6=(9.9+0.1)*8.6=86
9.9x8.6+0.86=9.9×8.6+(0.1×8.6)=8.6×(9.9+0.1)=8.6×10=86祝你学习天天向上,加油!!!!!!!!!
(10-0.1)*8.6+0.86=10*8.6-0.1*8.6+0.86=86
=(10-0.1)*8.6+0.86=10*8.6-0.1*8.6-0.86=86
(9.9+0.1)*8.6=86