题目是这样吗,我怎么感觉最前面也应该是7.28
7.28X3.1+7.9X7.28-7.28 =7.28X(3.1+7.9-1) =7.28X10 =72.8
可能你的题目有错 7.28X3.1+7.9X7.28-7.28 =7.28×3.1+7.28×7.9-7.28×1 =7.28×(3.1+7.9-1) =7.28×10 =72.8
7.28_2.28×1.5用简便方法计算 =7.28×(1-1.5) =7.28×(-0.5) =3.64
应该是小数点点错了,没有简便算法。 15×7.28-2.28×1.5 =1.5×72.8-2.28×1.5 =1.5×(72.8-2.28) =1.5×70.52 =105.78
=7.28x(3.1+7.9-1) =7.28x10 =72.8
7.28减2.28乘1.5用简便方法计算 =7.28-2.28-2.28x0.5 =5-1.14 =3.86
图
用简便方法计算 7.28-2.28×1.5 =7.28-2.28-2.28x0.5 =5-1.14 =3.86
7.28×3.1 +7.9×7.28-7.28 =7.28×(3.1 +7.9-1) =7.28×10 =72.8