作业帮 > 数学 > 作业

用简便方法计算,并要写出主要的简算过程.

来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/01 22:25:35
用简便方法计算,并要写出主要的简算过程.
7
11

7
11+
1
5+
4
11+
3
5,
=(
7
11+
4
11)+(
1
5+
3
5),
=1+
4
5,
=1
4
5;
②12.5×8×4×0.25,
=(12.5×8)×(4×0.25),
=100×1,
=100;
③5-
9

45
8-
3
5,
=5−
9

8
45−
3
5,
=5−
2
5−
3
5,
=5-(
2
5+
3
5),
=5-1,
=4;
④4.9×6.4+14×0.36-6.4×3.5,
=(4.9-3.5)×6.4+14×0.36,
=1.4×6.4+1.4×3.6,
=1.4×(6.4+3.6),
=1.4×10,
=14.