题目内容
计算:
+
+
+…+
.
| 1 |
| x(x+1) |
| 1 |
| (x+1)(x+2) |
| 1 |
| (x+2)(x+3) |
| 1 |
| (x+2008)(x+2009) |
分析:先把原式的分母进行拆分,找出规律进行计算即可.
解答:解:∵
=
-
,
=
-
,
∴
=
-
,
∴原式=
-
+
-
+
-
+…+
-
=
-
=
.
| 1 |
| x(x+1) |
| 1 |
| x |
| 1 |
| x+1 |
| 1 |
| (x+1)(x+2) |
| 1 |
| x+1 |
| 1 |
| x+2 |
∴
| 1 |
| (x+n)(x+n+1) |
| 1 |
| x+n |
| 1 |
| x+n+1 |
∴原式=
| 1 |
| x |
| 1 |
| x+1 |
| 1 |
| x+1 |
| 1 |
| x+2 |
| 1 |
| x+2 |
| 1 |
| x+3 |
| 1 |
| x+2008 |
| 1 |
| x+2009 |
=
| 1 |
| x |
| 1 |
| x+2009 |
=
| 2009 |
| x(x+2009) |
点评:本题考查的是分式的加减法,熟知异分母的分数相加减的法则是解答此题的关键.
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