1、03数列一、选择题1.(北京7).已知等差数列中,,,若,则数列的前5项和等于(C)A.30B.45C.90D.1862.(广东4)记等差数列{an}的前n项和为Sn,若S1=4,S4=20,则该数列的公差d=(B)A.7B.6C.3D.23.(宁夏8)设等比数列的公比q=2,前n项和为Sn,则=(C)A.B.C.D.4.(江西5)在数列中,,,则(A)A.B.C.D.5.(全国Ⅰ7)已知等比数列满足,则(A)A.64B.81C.128D.2436.(福建3)设是等差数列,若,则数列前8项和为( C )A.12
2、8B.80C.64D.567.(上海14)若数列是首项为,公比为的无穷等比数列,且各项的和为a,则的值是( B )A.1B.2C.D.8.(天津4)若等差数列的前5项和,且,则(B)A.12B.13C.14D.159.(浙江4)已知是等比数列,,则公比=(D)(A)(B)(C)2(D)10.(重庆1)已知{an}为等差数列,a2+a8=12,则a5等于(C)(A)4(B)5(C)6(D)711.(陕西4)已知是等差数列,,,则该数列前10项和等于(B)A.64B.100C.110D.120二、填空题1.(安徽1