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问题 填空题

设直线y=kx+k-1和直线y=（k+1）x+k（k是正整数）与x轴围成的三角形面积为Sk，则S1+S2+S3+…+S2012的值是            ．

答案

方程组 的解为 ，

所以直线的交点是（﹣1，﹣1），

直线y=kx+k﹣1与x轴的交点为 ，y=（k+1）x+k与x轴的交点为（ ，0），

∴Sk==，

所以 S1+S2+S3+…+S2012=（1﹣+﹣+﹣+…+）

=×（1﹣）=×=．

问答题

Ade, a keen pottery collector, saw a notice for an auction of Bede pottery in the January edition of Antiques News. He travelled 300 kilometres to attend the auction in order to bid for a particularly rare example of Bede pottery, specifically mentioned in the lists of items to be auctioned. However, when he got to the auction site he found a notice outside, stating that the auction had been cancelled. Ade went into a nearby antique shop and saw an example of the type of pottery he had come to bid for. The price ticket stated that it was ￡500, but Ade said he was only willing to pay ￡350 for it. The shopkeeper, Chip, said he would sell it for ￡400 and as Ade said he would like time to think about it over lunch, Chip agreed not to sell it before Ade returned.However, when Ade returned to buy the pottery, he found that Chip had already sold it to someone else, who had paid ￡450 for it.Required:In the context of contract law, advise Ade whether he can take action against:

(a) the auctioneers, for the expense of his travel to the auction; and
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单项选择题

低压架空铜线的最小截面为（）mm2。

A、6

B、10

C、16

D、25
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