题目内容
观察下列算式，并进行计算．
=
×（
-
），
=
×（
-
），求
+
+
+…+
的值．
| 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 |
| 2007×2009 |
原式=
(
-
)+
(
-
)+…+
(
-
)
=
(1-
+
-
+
-
+…+
-
)=
(1-
)=
×
’=
| 1 |
| 2 |
| 1 |
| 1 |
| 1 |
| 3 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 5 |
| 1 |
| 2 |
| 1 |
| 2007 |
| 1 |
| 2009 |
=
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 5 |
| 1 |
| 5 |
| 1 |
| 7 |
| 1 |
| 2007 |
| 1 |
| 2009 |
| 1 |
| 2 |
| 1 |
| 2009 |
| 1 |
| 2 |
| 2008 |
| 2009 |
| 1004 |
| 2009 |
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