题目内容
脱式计算.
[90-(18.9+2.88)]÷1.8
4×(2.44-1.8)÷0.4
-
+(
-
)
-(
+
)+
.
[90-(18.9+2.88)]÷1.8
4×(2.44-1.8)÷0.4
4 |
5 |
2 |
3 |
3 |
5 |
1 |
15 |
4 |
5 |
3 |
20 |
3 |
10 |
3 |
4 |
分析:(3)可以去掉括号,运用加法结合律简算;其余题目根据先算乘除,再算加减,有括号的先算括号里面的运算顺序计算.
解答:解:(1)[90-(18.9+2.88)]÷1.8,
=[90-21.78]÷1.8,
=68.22÷1.8,
=37.9;
(2)4×(2.44-1.8)÷0.4,
=4×0.64÷0.4,
=6.4;
(3)
-
+(
-
),
=
-
+
-
,
=(
+
)-(
+
),
=
-
,
=
;
(4)
-(
+
)+
,
=
-
+
,
=
-
+
,
=
.
=[90-21.78]÷1.8,
=68.22÷1.8,
=37.9;
(2)4×(2.44-1.8)÷0.4,
=4×0.64÷0.4,
=6.4;
(3)
4 |
5 |
2 |
3 |
3 |
5 |
1 |
15 |
=
4 |
5 |
2 |
3 |
3 |
5 |
1 |
15 |
=(
4 |
5 |
3 |
5 |
2 |
3 |
1 |
15 |
=
7 |
5 |
11 |
15 |
=
2 |
3 |
(4)
4 |
5 |
3 |
20 |
3 |
10 |
3 |
4 |
=
4 |
5 |
9 |
20 |
3 |
4 |
=
16 |
20 |
9 |
20 |
15 |
20 |
=
11 |
10 |
点评:本题考查了基本的分数加减法的运算和小数的四则混合运算,注意把结果化成最简分数.
![](http://thumb2018.1010pic.com/images/loading.gif)
练习册系列答案
相关题目