题目内容
用自己喜欢的方法计算．
①
+
+
②1-
-
③
-
+
．
①
| 9 |
| 20 |
| 2 |
| 3 |
| 11 |
| 20 |
| 1 |
| 14 |
| 2 |
| 7 |
| 7 |
| 9 |
| 2 |
| 3 |
| 5 |
| 6 |
考点：分数的加法和减法
专题：运算顺序及法则
分析：①根据加法的交换律简算即可；
②③按从左到右的运算顺序计算．
②③按从左到右的运算顺序计算．
解答：
解：①
+
+
=
+
+
=1+
=1+
②1-
-
=
-
=
③
-
+
=
+
=
| 9 |
| 20 |
| 2 |
| 3 |
| 11 |
| 20 |
=
| 9 |
| 20 |
| 11 |
| 20 |
| 2 |
| 3 |
=1+
| 2 |
| 3 |
=1+
| 2 |
| 3 |
②1-
| 1 |
| 14 |
| 2 |
| 7 |
=
| 13 |
| 14 |
| 2 |
| 7 |
=
| 9 |
| 14 |
③
| 7 |
| 9 |
| 2 |
| 3 |
| 5 |
| 6 |
=
| 1 |
| 9 |
| 5 |
| 6 |
=
| 17 |
| 18 |
点评：本题关键是明确分数加减混合运算的计算法则，要注意能简算的要简算．
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