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已知递增数列{an}满足an+1﹣an=an﹣an﹣1(n≥2),a1=2,且a2﹣1,a3,a4+5成等比数列. (1)求an; (2)若,求数列{bn}的前n项和Sn.
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高三下学期数学《》真题及答案
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高一上学期英语
高一下学期化学
高一下学期物理
高三下学期数学
高三上学期数学
高一下学期英语
教案备课库
高一上学期生物
高一下学期生物
高二上学期数学
高二上学期物理
高二上学期英语
高二上学期生物
高二下学期数学
高二上学期化学
高二下学期物理