题目
题型:填空题难度:简单来源:不详
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073322-70078.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073322-20335.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073322-39167.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073323-59230.gif)
答案
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073323-15404.gif)
解析
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073323-89218.gif)
核心考点
举一反三
1×2 =
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073320-39766.png)
2×3 =
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073320-39766.png)
3×4 =
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073320-39766.png)
由以上三个等式相加,可得
1×2+2×3+3×4 =
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073320-39766.png)
读完以上材料,请你计算下列各题:
(1)1×2+2×3+3×4+···+10×11(写出过程);
(2)1×2+2×3+3×4+···+n×(n+1) = _________;
(3)1×2×3+2×3×4+3×4×5+···+7×8×9 = _________。
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073316-36006.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073316-24695.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073316-16915.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073317-13527.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073317-38334.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073317-96357.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073317-80724.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073317-66334.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073318-34592.gif)
A.6a | B.6a2 |
C.5a | D.5a2 |
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073311-67509.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073312-93227.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073312-35375.gif)
(取整符号
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073312-38496.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073312-21084.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073312-65209.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073312-61023.gif)
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073313-55332.gif)
A.1 | B.2 | C.3 | D.4 |
![](http://img.shitiku.com.cn/uploads/allimg/20190817/20190817073310-29080.gif)
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