题目内容
脱式计算（能简算要简算）
①
+
+
+
②
+
-
③
+
-
+
④
+（
-
）+
．
①
| 6 |
| 7 |
| 2 |
| 15 |
| 1 |
| 7 |
| 13 |
| 15 |
②
| 19 |
| 21 |
| 5 |
| 7 |
| 13 |
| 14 |
③
| 2 |
| 3 |
| 5 |
| 9 |
| 2 |
| 3 |
| 5 |
| 9 |
④
| 5 |
| 9 |
| 1 |
| 4 |
| 1 |
| 9 |
| 3 |
| 4 |
考点：分数的简便计算
专题：运算顺序及法则
分析：①运用加法交换与结合律简算；
②先通分华威同分母分数再加减即可；
③运用加法结合律简算；
④先去括号运用加法交换律与结合律简算．
②先通分华威同分母分数再加减即可；
③运用加法结合律简算；
④先去括号运用加法交换律与结合律简算．
解答：
解：①
+
+
+
=(
+
)+(
+
)
=1+1
=2；
②
+
-
=
+
-
=
；
③
+
-
+
=(
-
)+(
+
)
=
；
④
+（
-
）+
=
+
-
+
=(
-
)+(
+
)
=
+1
=
．
| 6 |
| 7 |
| 2 |
| 15 |
| 1 |
| 7 |
| 13 |
| 15 |
=(
| 6 |
| 7 |
| 1 |
| 7 |
| 2 |
| 15 |
| 13 |
| 15 |
=1+1
=2；
②
| 19 |
| 21 |
| 5 |
| 7 |
| 13 |
| 14 |
=
| 38 |
| 42 |
| 30 |
| 42 |
| 39 |
| 42 |
=
| 29 |
| 42 |
③
| 2 |
| 3 |
| 5 |
| 9 |
| 2 |
| 3 |
| 5 |
| 9 |
=(
| 2 |
| 3 |
| 2 |
| 3 |
| 5 |
| 9 |
| 5 |
| 9 |
=
| 10 |
| 9 |
④
| 5 |
| 9 |
| 1 |
| 4 |
| 1 |
| 9 |
| 3 |
| 4 |
=
| 5 |
| 9 |
| 1 |
| 4 |
| 1 |
| 9 |
| 3 |
| 4 |
=(
| 5 |
| 9 |
| 1 |
| 9 |
| 1 |
| 4 |
| 3 |
| 4 |
=
| 4 |
| 9 |
=
| 13 |
| 9 |
点评：本题主要考查了分数的简便计算．要注意分析式中数据，运用合适的简便方法计算．
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