Question

3.8×8.9+2.1×3.9-3.8怎么简算？

Answer 1

脱式计算3.8×8.9+2.1×3.9-3.8
解题思路:四则运算规则(按顺序计算,先算乘除后算加减,有括号先算括号,有乘方先算乘方)即脱式运算(递等式计算)需在该原则前提下进行

解题过程:
3.8×8.9+2.1×3.9-3.8

=3.8×(8.9+2.1-1)+2.1×0.1

=3.8×10+2.1×0.1

=38+0.21

=38.21

存疑请追问,满意请采纳

Answer 2

本题应该是2.1×3.8，否则简便计算没有意义。
3.8×8.9+2.1×3.8-3.8
=3.8×(8.9+2.1-1)
=3.8×10
=38

Answer 3

3.8×8.9+2.1×3.9-3.8
=3.8×8.9+2.1×(3.8+0.1)-3.8
=3.8×8.9+2.1×3.8+2.1×0.1-3.8
=3.8×(8.9+2.1-1)+2.1×0.1
=3.8×10+0.21
=38+0.21
=38.21

Answer 4

3.8×8.9+2.1×3.9-3.8
=3.8*8.9-3.8+2.1*3.9
=3.8*（8.9-1）+2.1*3.9
=3.8*7.9+2.1*3.9
=30.02+8.19
=38.21