题目内容
用简便方法计算
(1)
|
(2)
|
(3)
|
分析:(1)先算小括号里面的减法,再算括号外的减法;
(2)(3)运用加法交换律和结合律简算.
(2)(3)运用加法交换律和结合律简算.
解答:解:(1)
-(
-
),
=
-
,
=
;
(2)
+
+
+
,
=(
+
)+(
+
),
=1+1,
=2;
(3)
+
-
+
,
=(
+
)+(
-
),
=1+0,
=1.
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 8 |
=
| 1 |
| 2 |
| 1 |
| 8 |
=
| 3 |
| 8 |
(2)
| 3 |
| 4 |
| 3 |
| 7 |
| 1 |
| 4 |
| 4 |
| 7 |
=(
| 3 |
| 4 |
| 1 |
| 4 |
| 4 |
| 7 |
| 3 |
| 7 |
=1+1,
=2;
(3)
| 11 |
| 15 |
| 3 |
| 8 |
| 3 |
| 8 |
| 4 |
| 15 |
=(
| 11 |
| 15 |
| 4 |
| 15 |
| 3 |
| 8 |
| 3 |
| 8 |
=1+0,
=1.
点评:此题主要考查分数加减混合运算,合理运用运算定律进行简便计算.
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