5.1×8.4-2.84用简算计算如下:5.1×8.4-2.84=(5+0.1)×8.4-2.84=5×8.4+0.1×8.4-2.84=5×8.4+(0.84-2.84)=42-2=40
5.1x8.4-2.84 =5x8.4+0.1x8.4-2.84 =10x8.4/2+0.84-2.84 =42-2 =40
5.1x8.4-2.84=5x8.4+0.1x8.4-2.84=10x8.4/2+0.84-2.84=42-2=40