题目内容
下面各题,怎样算简便就怎样算.
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2-
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分析:(1)根据加法交换律进行简算;
(2)根据减法的性质进行简算;
(3)根据加法交换律进行简算;
(4)根据减法的性质进行简算;
(5)根据加法交换律和结合律进行简算;
(6)根据加法交换律和结合律,以及减法的性质进行简算.
(2)根据减法的性质进行简算;
(3)根据加法交换律进行简算;
(4)根据减法的性质进行简算;
(5)根据加法交换律和结合律进行简算;
(6)根据加法交换律和结合律,以及减法的性质进行简算.
解答:解:(1)
+
-
=
-
+
=
;
(2)2-
-
=2-(
+
)
=2-1
=1;
(3)
+
+
=
+
+
=1+
=1
;
(4)
-(
+
)
=
-
-
=
-
=
;
(5)
+(
+
)
=(
+
)+
=1+
=1
;
(6)
-
+
-
=(
+
)-(
+
)
=1-1
=0.
| 4 |
| 7 |
| 1 |
| 6 |
| 4 |
| 7 |
=
| 4 |
| 7 |
| 4 |
| 7 |
| 1 |
| 6 |
=
| 1 |
| 6 |
(2)2-
| 5 |
| 9 |
| 4 |
| 9 |
=2-(
| 5 |
| 9 |
| 4 |
| 9 |
=2-1
=1;
(3)
| 3 |
| 5 |
| 7 |
| 8 |
| 2 |
| 5 |
=
| 3 |
| 5 |
| 2 |
| 5 |
| 7 |
| 8 |
=1+
| 7 |
| 8 |
=1
| 7 |
| 8 |
(4)
| 7 |
| 9 |
| 1 |
| 9 |
| 1 |
| 3 |
=
| 7 |
| 9 |
| 1 |
| 9 |
| 1 |
| 3 |
=
| 2 |
| 3 |
| 1 |
| 3 |
=
| 1 |
| 3 |
(5)
| 1 |
| 4 |
| 2 |
| 5 |
| 3 |
| 4 |
=(
| 1 |
| 4 |
| 3 |
| 4 |
| 2 |
| 5 |
=1+
| 2 |
| 5 |
=1
| 2 |
| 5 |
(6)
| 5 |
| 6 |
| 3 |
| 10 |
| 1 |
| 6 |
| 7 |
| 10 |
=(
| 5 |
| 6 |
| 1 |
| 6 |
| 3 |
| 10 |
| 7 |
| 10 |
=1-1
=0.
点评:此题主要考查分数的四则混合运算的运算顺序和应用运算定律进行简便计算.
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