题目内容
观察式子:
=
(1-
),
=
(
-
),
=
(
-
),….由此计算:
+
+
+…+
=______.
1 |
1×3 |
1 |
2 |
1 |
3 |
1 |
3×5 |
1 |
2 |
1 |
3 |
1 |
5 |
1 |
5×7 |
1 |
2 |
1 |
5 |
1 |
7 |
1 |
1×3 |
1 |
3×5 |
1 |
5×7 |
1 |
2009×2011 |
原式=
(1-
+
-
+…+
-
)=
×(1-
)=
×
=
.
1 |
2 |
1 |
3 |
1 |
3 |
1 |
5 |
1 |
2009 |
1 |
2011 |
1 |
2 |
1 |
2011 |
1 |
2 |
2010 |
2011 |
1005 |
2011 |
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