原式=3.6x0.51+0.36x10x0.28+0.036x100x0.21=3.6x0.51+3.6x0.28+3.6x0.21=3.6x(0.51+0.28+0.21)=3.6x1=3.6供参考。
3.6×0.51+0.36×2.8+0.036×21=3.6×0.51+3.6×0.28+3.6×0.21=3.6×(0.51+0.28+0.21)=3.6×1=3.6
