摘要：计算: ⑴11-13+18 ⑵-32-9÷3+()×12
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先阅读，再解题：
+
+
+
+…+
=（1-
）+（
-
）+（
-
）+9
-
）+…+（
-
）=1-
=
参照上述解法计算：
+
+
+
+…+
．
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| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 4×5 |
| 1 |
| 99×100 |
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 3 |
| 1 |
| 4 |
| 1 |
| 4 |
| 1 |
| 5 |
| 1 |
| 99 |
| 1 |
| 100 |
| 1 |
| 100 |
| 99 |
| 100 |
参照上述解法计算：
| 1 |
| 1×3 |
| 1 |
| 3×5 |
| 1 |
| 5×7 |
| 1 |
| 7×9 |
| 1 |
| 2011×2013 |
观察下列各式：
-
=
=
，
-
=
=
，…，
-
=
．根据上式所反映出来的规律，请你计算：
+
+
+…+
= ．
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| 1 |
| 3 |
| 1 |
| 5 |
| 2 |
| 15 |
| 2 |
| 3×5 |
| 1 |
| 5 |
| 1 |
| 7 |
| 2 |
| 35 |
| 2 |
| 5×7 |
| 1 |
| n |
| 1 |
| n+2 |
| 2 |
| n(n+2) |
| 1 |
| 1×3 |
| 1 |
| 3×5 |
| 1 |
| 5×7 |
| 1 |
| n(n+2) |