题目内容
(2011•常德)先找规律,再填数:
+
﹣1=
,
+
﹣
=
,
+
﹣
=
,
+
﹣
=
,则
+
﹣ =
.
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751894168.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751910231.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751910231.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751941231.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751941233.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751910231.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751972260.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752003231.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752019240.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751941231.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752035279.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752066229.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752081240.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004751941233.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752113276.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752128332.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752144337.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752159481.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752175347.gif)
通过观察得:
每个算式第一个加数的分母依次是1,3,5,7,…,是首项为1,公差为2的等差数列,每个算式的减数的分母依次是1,2,3,4,…即是第几个算式,
设要求的是第n个算式,
则:1+(n﹣1)×2=2011,
解得:n=1006,
故答案为:
.![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/2014082300475236285.gif)
每个算式第一个加数的分母依次是1,3,5,7,…,是首项为1,公差为2的等差数列,每个算式的减数的分母依次是1,2,3,4,…即是第几个算式,
设要求的是第n个算式,
则:1+(n﹣1)×2=2011,
解得:n=1006,
故答案为:
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/20140823004752175347.gif)
![](http://thumb.zyjl.cn/pic2/upload/papers/20140823/2014082300475236285.gif)
![](http://thumb.zyjl.cn/images/loading.gif)
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