題目列表(包括答案和解析)
(06年廣東卷)(14分)
已知公比為的無窮等比數(shù)列各項(xiàng)的和為9,無窮等比數(shù)列各項(xiàng)的和為.
(Ⅰ)求數(shù)列的首項(xiàng)和公比;
(Ⅱ)對給定的,設(shè)是首項(xiàng)為,公差為的等差數(shù)列.求數(shù)列的前10項(xiàng)之和;
(Ⅲ)設(shè)為數(shù)列的第項(xiàng),,求,并求正整數(shù),使得
存在且不等于零.
(注:無窮等比數(shù)列各項(xiàng)的和即當(dāng)時(shí)該無窮數(shù)列前n項(xiàng)和的極限)
(1)求數(shù)列{an}的首項(xiàng)a1和公比q;
(2)對給定的k(k=1,2,…,n),設(shè)T(k)是首項(xiàng)為ak,公差為2ak-1的等差數(shù)列,求數(shù)列T(2)的前10項(xiàng)之和;
(3)設(shè)bi為數(shù)列T(i)的第i項(xiàng),Sn=b1+b2+…+bn,求Sn,并求正整數(shù)m(m>1),使得存在且不等于零.
(注:無窮等比數(shù)列各項(xiàng)的和即當(dāng)n→∞時(shí)該無窮等比數(shù)列前n項(xiàng)和的極限)
已知公比為q(0<q<1)的無窮等比數(shù)列{an}各項(xiàng)的和為9,無窮等比數(shù)列{an2}各項(xiàng)的和為。
(Ⅰ)求數(shù)列{an}的首項(xiàng)a1和公比q:
(Ⅱ)對給定的k(k=1,2,…,n),設(shè)T{k}是首項(xiàng)為ak,公差為2ak-1的等差數(shù)列,求數(shù)列T{2}的前10項(xiàng)之和:
(Ⅲ)設(shè)bi為數(shù)列的第i項(xiàng),sn=b1+b2+…+bn,求sn,并求正整數(shù)m(m>1),使得存在且不等于零。
(注:無窮等比數(shù)列各項(xiàng)的和即當(dāng)n時(shí)該無窮等比數(shù)列前n項(xiàng)和的極限)
(Ⅰ)證明{bn}為等比數(shù)列;
(Ⅱ)如果無窮等比數(shù)列{bn}各項(xiàng)的和S=,求數(shù)列{an}的首項(xiàng)a1和公差d.
(注:無窮數(shù)列各項(xiàng)的和即當(dāng)n→∞時(shí)數(shù)列前n項(xiàng)和的極限)
已知{an}是各項(xiàng)均為正數(shù)的等差數(shù)列,lga1、lga2、lga4成等差數(shù)列,又bn=,n=1,2,3….
(Ⅰ)證明{bn}為等比數(shù)列;
(Ⅱ)如果無窮等比數(shù)列{bn}各項(xiàng)的和S=,求數(shù)列{an}的首項(xiàng)a1和公差d.
(注:無窮數(shù)列各項(xiàng)的和即當(dāng)n→∞時(shí)數(shù)列前n項(xiàng)和的極限)
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