题目内容
(2012?北京模拟)
-
+
-
+
.
| 5+6 |
| 5×6 |
| 6+7 |
| 6×7 |
| 7+8 |
| 7×8 |
| 8+9 |
| 8×9 |
| 9+10 |
| 9×10 |
分析:因为
=
+
,所以将算式中的数先写成这种形式,能结合的结合,再进行加减计算.
| a+b |
| ab |
| 1 |
| a |
| 1 |
| b |
解答:解:
-
+
-
+
,
=
+
-
-
+
+
-
-
+
+
,
=
+
,
=
.
| 5+6 |
| 5×6 |
| 6+7 |
| 6×7 |
| 7+8 |
| 7×8 |
| 8+9 |
| 8×9 |
| 9+10 |
| 9×10 |
=
| 1 |
| 5 |
| 1 |
| 6 |
| 1 |
| 6 |
| 1 |
| 7 |
| 1 |
| 7 |
| 1 |
| 8 |
| 1 |
| 8 |
| 1 |
| 9 |
| 1 |
| 9 |
| 1 |
| 10 |
=
| 1 |
| 5 |
| 1 |
| 10 |
=
| 3 |
| 10 |
点评:解决本题主要依据:
=
+
,将算式进行简算.
| a+b |
| ab |
| 1 |
| a |
| 1 |
| b |
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