题目内容
下列各题怎样计算简便就怎样算.
-
+
6-(
-
)
+
-
+
-(
+
).
4 |
5 |
11 |
15 |
1 |
10 |
6-(
3 |
4 |
2 |
5 |
4 |
7 |
7 |
8 |
3 |
7 |
1 |
8 |
4 |
5 |
2 |
15 |
1 |
3 |
分析:(1)按从左到右的顺序先算减法再算加法;
(2)(4)先算括号里面的,再算括号外的减法;
(3)可根据加法交换律与结合律计算.
(2)(4)先算括号里面的,再算括号外的减法;
(3)可根据加法交换律与结合律计算.
解答:解:(1)
-
+
=
+
,
=
;
(2)6-(
-
)
=6-
,
=5
;
(3)
+
-
+
,
=
-
+(
+
),
=
+1,
=1
;
(4)
-(
+
)
=
-
,
=
.
4 |
5 |
11 |
15 |
1 |
10 |
=
1 |
15 |
1 |
10 |
=
1 |
6 |
(2)6-(
3 |
4 |
2 |
5 |
=6-
7 |
20 |
=5
13 |
20 |
(3)
4 |
7 |
7 |
8 |
3 |
7 |
1 |
8 |
=
4 |
7 |
3 |
7 |
7 |
8 |
1 |
8 |
=
1 |
7 |
=1
1 |
7 |
(4)
4 |
5 |
2 |
15 |
1 |
3 |
=
4 |
5 |
7 |
15 |
=
1 |
3 |
点评:完成本题要细心,注意通分约分.
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