We first introduce methods of finding the sum of the first n terms for an arithmetic sequence of higher order.

我们首先介绍了高阶等差数列前 n 项和的求解方法。

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You have n branches on the tree and you count the number of leaves and sum them up.

你计算了树上n个树枝，并数出树叶的数目并计算出总和。

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N ow, work in groups to sum up the names of the clothes we have learnt and each group asks one student to report the results to the class.

学生进行小组讨论，归纳出所学过的服装名称。然后推荐一位代表向全班学生汇报，看哪一组归纳得最多。

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You have n branches on the tree and you count the number of leaves and sum them up.

一共有n根树枝,你数了叶子的数量然后把他们加起来

耶鲁公开课 - 金融市场课程节选

The sum of the previous two.

加上第n-2个月的兔子对数。

麻省理工公开课 - 计算机科学及编程导论课程节选

N'Zogbia joined Newcastle in 2004, with the Magpies paying a nominal sum to Le Havre for their youth team player.

BBC: N'Zogbia ready to leave Newcastle