已知数列{an}满足a1=1,a2=a(a>0),数列{bn}=an*an+
来源:学生作业帮 编辑:作业帮 分类:数学作业 时间:2024/05/21 20:08:41
已知数列{an}满足a1=1,a2=a(a>0),数列{bn}=an*an+
bn=an*an+1 若{an}是等差数列,且b3=12,求a及an通项⑵若{an}是等比数列,求{bn}的前n项的和sn
bn=an*an+1 若{an}是等差数列,且b3=12,求a及an通项⑵若{an}是等比数列,求{bn}的前n项的和sn
(1){an}是等差数列,a1=1,a2=a(a>0),
an=1+(n-1)(a-1)
a3=2a-1,a4=3a-2
b3=a3*a4=(2a-1)(3a-2)=12
a=2,或-5/6(舍去)
所以a=2,an=n
(2){an}是等比数列,a1=1,a2=a(a>0),
a3=a^2,a4=a^3
b3=a3*a4=a^5=12
a=5次根号12
an=(5次根号12)^(n-1)
bn=an*an+1=(5次根号12)^(n-1)(5次根号12)^n=(5次根号12)^(2n-1)
{bn}的前n项的和sn=[1-(5次根号12)^(2n+1)]/[1-(5次根号12)^2
an=1+(n-1)(a-1)
a3=2a-1,a4=3a-2
b3=a3*a4=(2a-1)(3a-2)=12
a=2,或-5/6(舍去)
所以a=2,an=n
(2){an}是等比数列,a1=1,a2=a(a>0),
a3=a^2,a4=a^3
b3=a3*a4=a^5=12
a=5次根号12
an=(5次根号12)^(n-1)
bn=an*an+1=(5次根号12)^(n-1)(5次根号12)^n=(5次根号12)^(2n-1)
{bn}的前n项的和sn=[1-(5次根号12)^(2n+1)]/[1-(5次根号12)^2
已知数列{an}满足a1=1,a2=a(a>0),数列{bn}=an*an+
已知数列An满足:a1=1,a2=a(a>0),数列Bn=AnAn+1
已知数列{an}满足:a1=1,a2=a(a>0),数列{bn}满足:bn=anan+2(n∈N*)
已知数列{an},如果数列{bn}满足b1=a1,bn=an+a(n-1)则称数列{bn}是数列{an}的生成数列
给定数列an={a1,a2,a3.an},bn=a(n+1)-an
已知数列{an}{bn}满足a1=1,a2=3,b(n+1)/bn=2,bn=a(n+1)-an,(n∈正整数),求数列
已知数列an,bn满足a1=1,a2=3,(b(n)+1)/bn=2,bn=a(n+1)-an,(n∈正整数)
已知数列An满足:a1=1,a2=a(a>0),数列Bn=AnAn+1 (1)若AN是等差数列,且B3=12,求...
高一数学题已知数列An满足:a1=1,a2=a(a>0),数列Bn=AnAn+1 (1)若AN是...
数列an中,a1=1,a2=2数列bn满足an+1+(-1)n次an,a属于N* (1)若an等差数列...
已知两个等比数列{an},{bn}满足a1=a(a>0),b1-a1=1,b2-a2=2,b3-a3=3,若数列{an}
数列{an} {bn}满足:a1=0 a2=1 a(n+2)=[an+a(n+1)]/2 bn=a(n+1)-an 求证