题目内容
|
|
|
5-
|
分析:(1)(2)按照先算括号里面的,再算括号外面的顺序解答;
(3)运用加法交换律和结合律解答.
(3)运用加法交换律和结合律解答.
解答:解:(1)
-(
-
),
=
-
,
=
;
(2)
-(
+
),
=
-
,
=
;
(3)
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2.
| 4 |
| 5 |
| 7 |
| 10 |
| 13 |
| 20 |
=
| 4 |
| 5 |
| 1 |
| 20 |
=
| 3 |
| 4 |
(2)
| 9 |
| 10 |
| 1 |
| 6 |
| 2 |
| 3 |
=
| 9 |
| 10 |
| 5 |
| 6 |
=
| 1 |
| 15 |
(3)
| 11 |
| 12 |
| 5 |
| 8 |
| 3 |
| 8 |
| 1 |
| 12 |
=(
| 11 |
| 12 |
| 1 |
| 12 |
| 5 |
| 8 |
| 3 |
| 8 |
=1+1,
=2.
点评:(1)按照四则运算顺序正确进行计算,(2)运用加法简便算法解决问题,是本题考查知识点.
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