题目内容
下面各题怎样算简便就怎样算.
|
2-
|
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|
|
|
分析:(1)根据加法交换律进行计算;
(2)根据连减的性质进行计算;
(3)根据加法交换律进行计算;
(4)根据加法交换律和结合律、减法的性质进行计算;
(5)根据加法交换律进行计算;
(6)根据加法交换律进行计算.
(2)根据连减的性质进行计算;
(3)根据加法交换律进行计算;
(4)根据加法交换律和结合律、减法的性质进行计算;
(5)根据加法交换律进行计算;
(6)根据加法交换律进行计算.
解答:解:
(1)
+
-
,
=
-
+
,
=
;
(2)2-
-
,
=2-(
+
),
=2-1,
=1;
(3)
+
+
,
=
+
+
,
=1+
,
=1
;
(4)
-
+
-
,
=(
+
)-(
+
),
=1-1,
=0;
(5)
+
+
,
=
+
+
,
=1+
,
=1
;
(6)
+
-
,
=
-
+
,
=
.
(1)
| 4 |
| 7 |
| 1 |
| 6 |
| 4 |
| 7 |
=
| 4 |
| 7 |
| 4 |
| 7 |
| 1 |
| 6 |
=
| 1 |
| 6 |
(2)2-
| 7 |
| 9 |
| 2 |
| 9 |
=2-(
| 7 |
| 9 |
| 2 |
| 9 |
=2-1,
=1;
(3)
| 3 |
| 5 |
| 7 |
| 8 |
| 2 |
| 5 |
=
| 3 |
| 5 |
| 2 |
| 5 |
| 7 |
| 8 |
=1+
| 7 |
| 8 |
=1
| 7 |
| 8 |
(4)
| 5 |
| 6 |
| 3 |
| 10 |
| 1 |
| 6 |
| 7 |
| 10 |
=(
| 5 |
| 6 |
| 1 |
| 6 |
| 3 |
| 10 |
| 7 |
| 10 |
=1-1,
=0;
(5)
| 2 |
| 5 |
| 1 |
| 3 |
| 3 |
| 5 |
=
| 2 |
| 5 |
| 3 |
| 5 |
| 1 |
| 3 |
=1+
| 1 |
| 3 |
=1
| 1 |
| 3 |
(6)
| 5 |
| 12 |
| 5 |
| 9 |
| 5 |
| 12 |
=
| 5 |
| 12 |
| 5 |
| 12 |
| 5 |
| 9 |
=
| 5 |
| 9 |
点评:考查了运算定律与简便运算,四则混合运算.注意运算顺序和运算法则,灵活运用所学的运算律简便计算.
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