题目内容
下面各题怎样算简便就怎样算．
+
-
+
-
+
-
+
+
．
| 7 |
| 15 |
| 3 |
| 5 |
| 3 |
| 10 |
| 8 |
| 25 |
| 2 |
| 5 |
| 13 |
| 50 |
| 5 |
| 12 |
| 3 |
| 7 |
| 5 |
| 12 |
| 11 |
| 15 |
| 2 |
| 7 |
| 4 |
| 15 |
考点：分数的简便计算,分数的四则混合运算
专题：运算顺序及法则,运算定律及简算
分析：①②把分数化成同分母的分数进行计算即可．
③④运用加法的交换律及结合律进行计算即可．
③④运用加法的交换律及结合律进行计算即可．
解答：
解：①
+
-
=
+
-
=
②
+
-
=
+
-
=
③
+
-
=
-
+
=
④
+
+
=（
+
）+
=1
| 7 |
| 15 |
| 3 |
| 5 |
| 3 |
| 10 |
=
| 14 |
| 30 |
| 18 |
| 30 |
| 9 |
| 30 |
=
| 23 |
| 30 |
②
| 8 |
| 25 |
| 2 |
| 5 |
| 13 |
| 50 |
=
| 16 |
| 50 |
| 20 |
| 50 |
| 13 |
| 50 |
=
| 23 |
| 50 |
③
| 5 |
| 12 |
| 3 |
| 7 |
| 5 |
| 12 |
=
| 5 |
| 12 |
| 5 |
| 12 |
| 3 |
| 7 |
=
| 3 |
| 7 |
④
| 11 |
| 15 |
| 2 |
| 7 |
| 4 |
| 15 |
=（
| 11 |
| 15 |
| 4 |
| 15 |
| 2 |
| 7 |
=1
| 2 |
| 7 |
点评：此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算．
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