题目内容
计算:
+
+
+
+
+
+
+
+
+
+
+
=
| 1 |
| 2048 |
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 8 |
| 1 |
| 16 |
| 1 |
| 32 |
| 1 |
| 64 |
| 1 |
| 128 |
| 1 |
| 256 |
| 1 |
| 512 |
| 1 |
| 1024 |
| 1 |
| 2048 |
1
1
.分析:通过观察,从第三个分数开始,分母都是前一个分母的2倍,于是可以把分数拆成两个分数相减的形式,然后通过加减相互抵消,最后剩下
+1-
,故结果为1.
| 1 |
| 2048 |
| 1 |
| 2048 |
解答:解:
+
+
+
+
+
+
+
+
+
+
+
,
=
+1-
+
-
+
-
+
-
+…+
-
,
=
+1-
,
=1;
故答案为:1.
| 1 |
| 2048 |
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 8 |
| 1 |
| 16 |
| 1 |
| 32 |
| 1 |
| 64 |
| 1 |
| 128 |
| 1 |
| 256 |
| 1 |
| 512 |
| 1 |
| 1024 |
| 1 |
| 2048 |
=
| 1 |
| 2048 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 8 |
| 1 |
| 8 |
| 1 |
| 16 |
| 1 |
| 1024 |
| 1 |
| 2048 |
=
| 1 |
| 2048 |
| 1 |
| 2048 |
=1;
故答案为:1.
点评:此题除了第一项,形如
=
-
,也可以,算
+
=
,
+
=
…,依次倒着相加,得出结论.
| 1 |
| 2a |
| 1 |
| a |
| 1 |
| 2a |
| 1 |
| 2048 |
| 1 |
| 2048 |
| 1 |
| 1024 |
| 1 |
| 1024 |
| 1 |
| 1024 |
| 1 |
| 512 |
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