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学习了分数和百分数的计算之后,徐老师组织全班学生开展了一次计算闯关比赛。徐老师首先出示第一关计算题:计算1/31+3/31+5/31+7/31+9/31。超威组代表谢德民抢先举手发言说:“这题是同分母分数相加,太简单了,分母不变,只要把分子相加就可以了。所得的和为(1+3+5+7+9)/31=25/31。”同一组的杜亚冉接着说:“这里的加数还是一组等差数列,因此还可
After learning the calculation of the scores and percentages, Mr. Xu organized the whole class to conduct a check-in contest. Xu first show off the first calculation: 1/31 +3 / 31 +5 / 31 +7 / 31 +9 / 31. Chaowei representatives on behalf of the ultra-Wei team first rang his hand and said: ”This question is the same denominator of the sum, too simple, denominator unchanged, as long as the sum of the molecules on it. The resulting and (1 +3 +5 + 7 + 9) / 31 = 25/31. “Du Ya Ran in the same group went on to say: ” The addend here is still a set of arithmetic progression, so