题目内容
简算.
(1)
+
+
+
(2)
+
-
-
(3)
-
+
-
(4)
-(
+
)
(5)
+
+(
+
).
(1)
2 |
9 |
1 |
8 |
3 |
8 |
1 |
9 |
(2)
5 |
8 |
1 |
8 |
3 |
10 |
1 |
10 |
(3)
5 |
6 |
4 |
9 |
1 |
6 |
2 |
9 |
(4)
9 |
10 |
1 |
10 |
2 |
5 |
(5)
4 |
9 |
1 |
8 |
2 |
9 |
3 |
8 |
考点:分数的加法和减法,分数的简便计算
专题:运算顺序及法则
分析:(1)(5)根据加法交换律和结合律简算;
(2)(4)根据减法的性质简算;
(3)根据加法结合律和减法的性质简算.
(2)(4)根据减法的性质简算;
(3)根据加法结合律和减法的性质简算.
解答:
解:(1)
+
+
+
=(
+
)+(
+
)
=
+
=
;
(2)
+
-
-
=
-(
+
)
=
-
=
;
(3)
-
+
-
=(
+
)-(
+
)
=1-
=
;
(4)
-(
+
)
=
-
-
=
-
=
;
(5)
+
+(
+
)
=(
+
)+(
+
)
=
+
=
.
2 |
9 |
1 |
8 |
3 |
8 |
1 |
9 |
=(
2 |
9 |
1 |
9 |
1 |
8 |
3 |
8 |
=
1 |
3 |
1 |
2 |
=
5 |
6 |
(2)
5 |
8 |
1 |
8 |
3 |
10 |
1 |
10 |
=
3 |
4 |
3 |
10 |
1 |
10 |
=
3 |
4 |
2 |
5 |
=
7 |
20 |
(3)
5 |
6 |
4 |
9 |
1 |
6 |
2 |
9 |
=(
5 |
6 |
1 |
6 |
4 |
9 |
2 |
9 |
=1-
2 |
3 |
=
1 |
3 |
(4)
9 |
10 |
1 |
10 |
2 |
5 |
=
9 |
10 |
1 |
10 |
2 |
5 |
=
4 |
5 |
2 |
5 |
=
2 |
5 |
(5)
4 |
9 |
1 |
8 |
2 |
9 |
3 |
8 |
=(
4 |
9 |
2 |
9 |
1 |
8 |
3 |
8 |
=
2 |
3 |
1 |
2 |
=
7 |
6 |
点评:本题考查了基本的分数的加减混合运算,要注意分析数据,选择合适的简算方法简算.
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