已知正项数列{an},{bn}满足:对任意正整数n,都有an,bn,a(n+1)成等差数列,bn,a(n+1),b（n＋1）成等比数列
已知正项数列{an},{bn}满足:对任意正整数n,都有an,bn,a(n+1)成等差数列,bn,a(n+1),b（n＋1）成等比数列
且a1＝10,a2＝15,（1）求数列{√bn}是等差数列,（2）求{an}{bn}的通项公式（3）设Sn＝1/a1＋1/a2＋.＋1/an,如果对任意正整数n,不等式2aSn＜2－bn/an,求实数a的取值范围
且a1＝10,a2＝15,（1）求数列{√bn}是等差数列,（2）求{an}{bn}的通项公式（3）设Sn＝1/a1＋1/a2＋.＋1/an,如果对任意正整数n,不等式2aSn＜2－bn/an,求实数a的取值范围
数学人气：523 ℃时间：2020-05-25 21:52:30
优质解答
1、an,bn,a(n+1),所以,2bn=an+a(n+1)推出,2(bn+1)=a(n+1)+a(n+2)bn,a(n+1),b(n+1),所以,a(n+1)^2=bn*b(n+1),推出,a(n+1)=根号下【bn*b(n+1)】,a(n+2)=根号下【b(n+1)*b(n+2)】,带入2(bn+1)=a(n+1)+a(n+2)并化简,得到...
我来回答
类似推荐
- 已知正项数列｛an｝｛bn｝满足,对任意正整数n,都有an,bn,an+1成等差数列,bn,an+1,bn+1成等比数列
- 正数列{an}和{bn}满足对任意自然数n,an,bn,an+1成等差数列,bn,an+1,bn+1成等比数列
- 已知正项数列{an},{bn}满足：a1=3,a2=6,{bn}是等差数列,且对任意正整数n,都有bn,根号an,bn+1成等比数
- 已知等差数列{an}的首项为a,公差为b,等比数列{bn}的首项为b,公比为a,a,b都是大于1的正整数
- {a} 、{b} 都是各项为正的数列,对任意的正整数n,都有an,bn^2,an+1 成等差数列,bn^2,an+1,bn+1^2成等比
猜你喜欢
- 1三根小棒,怎样能摆成12个直角?解图
- 26x^2-5xy-6y^2-2xz-23yz-20z^2 因式分解
- 3在……范围内变化 英语翻译
- 4maybe just so so
- 5辛弃疾破阵子表达作者怎样的思想感情?
- 6客、货两列火车从相距465千米的两地同时出发,相向而行.客车90千米/时,货车60千米/时,几小时后两车相距45千米?
- 7高中45分钟过关检测45分钟:生物(高二上册) 答案
- 8She is thirteen years old 改为一般疑问句
- 9HClO+H2SO3=H2SO4+HCl有这个方程吗
- 10英译汉：last year,I was invited to attend a party for "Tuesday's Child ",an organization that helps