1.28×8.6+1.44×4.3=1.28×2×4.3+1.44×4.3=4.3×(1.28×2+1.44)=4.3×(2.56+1.44)=4.3×4=17.2
8.6(1.28+0.72)=8.6X2=17.2
1.28X8.6十1.44x4.3=17.2
怎样子简便,到底怎么做?