题目内容
下面各题怎样算简便就怎样算
|
|
2-
|
分析:(1)通分计算;
(2)运用减法的性质及加法交换律简算;
(3)运用加法交换律简算.
(2)运用减法的性质及加法交换律简算;
(3)运用加法交换律简算.
解答:解:(1)
-
-
,
=
-
-
,
=-
;
(2)
-(
+
),
=
-
-
,
=(
-
)-
,
=
-
,
=
;
(3)2-
+
,
=2+(
-
),
=2+
,
=2
.
| 3 |
| 7 |
| 9 |
| 14 |
| 1 |
| 2 |
=
| 6 |
| 14 |
| 9 |
| 14 |
| 7 |
| 14 |
=-
| 5 |
| 7 |
(2)
| 5 |
| 8 |
| 1 |
| 12 |
| 3 |
| 8 |
=
| 5 |
| 8 |
| 1 |
| 12 |
| 3 |
| 8 |
=(
| 5 |
| 8 |
| 3 |
| 8 |
| 1 |
| 12 |
=
| 1 |
| 4 |
| 1 |
| 12 |
=
| 1 |
| 6 |
(3)2-
| 2 |
| 9 |
| 7 |
| 9 |
=2+(
| 7 |
| 9 |
| 2 |
| 9 |
=2+
| 5 |
| 9 |
=2
| 5 |
| 9 |
点评:考查了四则混合运算,灵活运用所学的运算定律简便计算.
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