题目内容
计算下面各题(能简便方法计算的,要写出简算过程)
4
+3.9+5
+6.1
×
+
×
4-(
+
÷
)
÷[
×(5
-3
)].
4
| 1 |
| 6 |
| 5 |
| 6 |
| 3 |
| 4 |
| 4 |
| 5 |
| 1 |
| 5 |
| 3 |
| 4 |
4-(
| 3 |
| 5 |
| 3 |
| 5 |
| 12 |
| 5 |
| 3 |
| 10 |
| 2 |
| 5 |
| 3 |
| 8 |
| 3 |
| 8 |
分析:算式(1)可根据加法交换律及结合律进行计算;
算式(2)可根据乘法分配律进行计算;
算式(3)、(4)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的.
算式(2)可根据乘法分配律进行计算;
算式(3)、(4)根据四则混合运算的运算顺序计算即可:先算乘除,再算加减,有括号的要先算括号里面的.
解答:解:(1)4
+3.9+5
+6.1
=(4
+5
)+(3.9+6.1),
=10+10,
=20;
(2)
×
+
×
=
×(
+
),
=
;
(3)4-(
+
÷
)
=4-(
+
×
),
=4-(
+
),
=4-(
+
),
=4-
,
=3
;
(4)
÷[
×(5
-3
)]
=
÷[
×2],
=
×
,
=
.
| 1 |
| 6 |
| 5 |
| 6 |
=(4
| 1 |
| 6 |
| 5 |
| 6 |
=10+10,
=20;
(2)
| 3 |
| 4 |
| 4 |
| 5 |
| 1 |
| 5 |
| 3 |
| 4 |
=
| 3 |
| 4 |
| 4 |
| 5 |
| 1 |
| 5 |
=
| 3 |
| 4 |
(3)4-(
| 3 |
| 5 |
| 3 |
| 5 |
| 12 |
| 5 |
=4-(
| 3 |
| 5 |
| 3 |
| 5 |
| 5 |
| 12 |
=4-(
| 3 |
| 5 |
| 1 |
| 4 |
=4-(
| 12 |
| 20 |
| 5 |
| 20 |
=4-
| 17 |
| 20 |
=3
| 3 |
| 20 |
(4)
| 3 |
| 10 |
| 2 |
| 5 |
| 3 |
| 8 |
| 3 |
| 8 |
=
| 3 |
| 10 |
| 2 |
| 5 |
=
| 3 |
| 10 |
| 5 |
| 4 |
=
| 3 |
| 8 |
点评:完成有关于分数的四则混合运算时要细心,注意通分、约分.
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