【简答题】数列 的前n项和为 ,若数列 的各项按如下规律排列: 有如下运算和结论:① ②数列 是等比 数列;③数列 的前n项和为 ④若 存在 ,使 其中正确的结论有 .(将你认 为正确的结论序号都填上)
【单选题】Woman: If the traffic weren’t so bad, we should be at home before eight o’clock. Man: Don’t be worried. We couldn’t fly home, anyway. Woman: We’ll be late for CCTV Spring Festival Gala. Man: But w...
【单选题】—Do they have a Music Festival? —________. [ ]
【单选题】We have no festival, nor ______, nor ceremony, not so-called Thanksgivings, by which the farmer expresses a sense of the sacredness of his calling, or is reminded of its sacred origin.
【简答题】We have just spent an unusual Spring Festival. Prepare a short passage in no less than 100 words.
【简答题】在等比数列 中, (1)求数列 的通项公式; (2)令 ,求数列 的前n项和 .
【简答题】在数列 中,已知 。 (Ⅰ)求证:数列 是等比数列; (Ⅱ)求数列 的通项公式; (Ⅲ)求数列 的前n项和 。