1.已知{an}前n项和Sn=1-5+9-13+17-21+...+(4n-3)*(-1)^(n-1)则S15+S22-S31=________2.已知等比数列{an}的前n项的和Sn=K*(3^n)+b,则K+b的值为_____3.数列{an}是公差不为零的等差数列,并且a5,a8,a13是等比数列{bn}的相邻三
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![1.已知{an}前n项和Sn=1-5+9-13+17-21+...+(4n-3)*(-1)^(n-1)则S15+S22-S31=________2.已知等比数列{an}的前n项的和Sn=K*(3^n)+b,则K+b的值为_____3.数列{an}是公差不为零的等差数列,并且a5,a8,a13是等比数列{bn}的相邻三](/uploads/image/z/3021402-66-2.jpg?t=1.%E5%B7%B2%E7%9F%A5%7Ban%7D%E5%89%8Dn%E9%A1%B9%E5%92%8CSn%3D1-5%2B9-13%2B17-21%2B...%2B%284n-3%29%2A%28-1%29%5E%28n-1%29%E5%88%99S15%2BS22-S31%3D________2.%E5%B7%B2%E7%9F%A5%E7%AD%89%E6%AF%94%E6%95%B0%E5%88%97%7Ban%7D%E7%9A%84%E5%89%8Dn%E9%A1%B9%E7%9A%84%E5%92%8CSn%3DK%2A%283%5En%29%2Bb%2C%E5%88%99K%2Bb%E7%9A%84%E5%80%BC%E4%B8%BA_____3.%E6%95%B0%E5%88%97%7Ban%7D%E6%98%AF%E5%85%AC%E5%B7%AE%E4%B8%8D%E4%B8%BA%E9%9B%B6%E7%9A%84%E7%AD%89%E5%B7%AE%E6%95%B0%E5%88%97%2C%E5%B9%B6%E4%B8%94a5%2Ca8%2Ca13%E6%98%AF%E7%AD%89%E6%AF%94%E6%95%B0%E5%88%97%7Bbn%7D%E7%9A%84%E7%9B%B8%E9%82%BB%E4%B8%89)
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