题目内容
计算题
(1)
+
+
+…+
;
(2)
+
+
+…+
.
(1)
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 2009×2010 |
(2)
| 1 |
| 1+2 |
| 1 |
| 1+2+3 |
| 1 |
| 1+2+3+4 |
| 1 |
| 1+2+3+…+2009+2010 |
(1)
+
+
+…+
=1-
+
-
+…+
-
=
;
(2)
+
+
+…+
=2×(
-
+…+
-
)
=
.
| 1 |
| 1×2 |
| 1 |
| 2×3 |
| 1 |
| 3×4 |
| 1 |
| 2009×2010 |
=1-
| 1 |
| 2 |
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 2009 |
| 1 |
| 2010 |
=
| 2009 |
| 2010 |
(2)
| 1 |
| 1+2 |
| 1 |
| 1+2+3 |
| 1 |
| 1+2+3+4 |
| 1 |
| 1+2+3+…+2009+2010 |
=2×(
| 1 |
| 2 |
| 1 |
| 3 |
| 1 |
| 2010 |
| 1 |
| 2011 |
=
| 2009 |
| 2011 |
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