作业帮2.5*3.8*0.4 6.7*4.5+4.5*13.3 2.06*0.9+2.06 0.8*[0.125+12.5+1.25] 用简便计算
来源：学生作业帮助网 编辑：作业帮 时间：2024/05/12 15:39:48
![2.5*3.8*0.4 6.7*4.5+4.5*13.3 2.06*0.9+2.06 0.8*[0.125+12.5+1.25] 用简便计算](/uploads/image/z/112178-2-8.jpg?t=2.5%2A3.8%2A0.4+6.7%2A4.5%2B4.5%2A13.3+2.06%2A0.9%2B2.06+0.8%2A%5B0.125%2B12.5%2B1.25%5D+%E7%94%A8%E7%AE%80%E4%BE%BF%E8%AE%A1%E7%AE%97)
2.5*3.8*0.4 6.7*4.5+4.5*13.3 2.06*0.9+2.06 0.8*[0.125+12.5+1.25] 用简便计算
2.5*3.8*0.4 6.7*4.5+4.5*13.3 2.06*0.9+2.06 0.8*[0.125+12.5+1.25] 用简便计算
2.5*3.8*0.4 6.7*4.5+4.5*13.3 2.06*0.9+2.06 0.8*[0.125+12.5+1.25] 用简便计算
2.5*3.8*0.4=2.5*0.4*3.8=1*3.8=3.8,
6.7*4.5+4.5*13.3=4.5*(6.7+13.3)=4.5*20=90,
2.06*0.9+2.06=2.06*(1-0.1)+2.06=2.06-0.206+2.06=1.854+2.06=3.914,
0.8*[0.125+12.5+1.250=0.8*0.125+0.8*12.5+0.8*1.250=0.1+10+1=11.1.
这还分简便不简便啊？第一个5/2,3.8.2/5,第一项和第三项之积是1，第二个，13.3+6.7=20，第个，直接乘，第四个，1.25=5/4 0.8=4/5 0.125=1.25*0.1 12.5=1.25*10